diff --git a/cmd/geth/admin.go b/cmd/geth/admin.go
index 2b9956638..17d711297 100644
--- a/cmd/geth/admin.go
+++ b/cmd/geth/admin.go
@@ -275,14 +275,13 @@ func (js *jsre) verbosity(call otto.FunctionCall) otto.Value {
 }
 
 func (js *jsre) startMining(call otto.FunctionCall) otto.Value {
-	_, err := call.Argument(0).ToInteger()
+	threads, err := call.Argument(0).ToInteger()
 	if err != nil {
 		fmt.Println(err)
 		return otto.FalseValue()
 	}
-	// threads now ignored
 
-	err = js.ethereum.StartMining()
+	err = js.ethereum.StartMining(int(threads))
 	if err != nil {
 		fmt.Println(err)
 		return otto.FalseValue()
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index fd7aae4c2..5da59ff3b 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -401,7 +401,7 @@ func startEth(ctx *cli.Context, eth *eth.Ethereum) {
 		}
 	}
 	if ctx.GlobalBool(utils.MiningEnabledFlag.Name) {
-		if err := eth.StartMining(); err != nil {
+		if err := eth.StartMining(ctx.GlobalInt(utils.MinerThreadsFlag.Name)); err != nil {
 			utils.Fatalf("%v", err)
 		}
 	}
diff --git a/cmd/mist/ui_lib.go b/cmd/mist/ui_lib.go
index a604e87ba..4653e0980 100644
--- a/cmd/mist/ui_lib.go
+++ b/cmd/mist/ui_lib.go
@@ -159,7 +159,7 @@ func (self *UiLib) RemoveLocalTransaction(id int) {
 
 func (self *UiLib) ToggleMining() bool {
 	if !self.eth.IsMining() {
-		err := self.eth.StartMining()
+		err := self.eth.StartMining(4)
 		return err == nil
 	} else {
 		self.eth.StopMining()
diff --git a/eth/backend.go b/eth/backend.go
index cdbe35b26..6be871138 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -267,7 +267,7 @@ func New(config *Config) (*Ethereum, error) {
 	eth.txPool = core.NewTxPool(eth.EventMux(), eth.chainManager.State, eth.chainManager.GasLimit)
 	eth.blockProcessor = core.NewBlockProcessor(stateDb, extraDb, eth.pow, eth.txPool, eth.chainManager, eth.EventMux())
 	eth.chainManager.SetProcessor(eth.blockProcessor)
-	eth.miner = miner.New(eth, eth.pow, config.MinerThreads)
+	eth.miner = miner.New(eth, eth.pow)
 	eth.miner.SetGasPrice(config.GasPrice)
 
 	eth.protocolManager = NewProtocolManager(config.ProtocolVersion, config.NetworkId, eth.eventMux, eth.txPool, eth.chainManager, eth.downloader)
@@ -368,7 +368,7 @@ func (s *Ethereum) ResetWithGenesisBlock(gb *types.Block) {
 	s.chainManager.ResetWithGenesisBlock(gb)
 }
 
-func (s *Ethereum) StartMining() error {
+func (s *Ethereum) StartMining(threads int) error {
 	eb, err := s.Etherbase()
 	if err != nil {
 		err = fmt.Errorf("Cannot start mining without etherbase address: %v", err)
@@ -376,7 +376,7 @@ func (s *Ethereum) StartMining() error {
 		return err
 	}
 
-	go s.miner.Start(eb)
+	go s.miner.Start(eb, threads)
 	return nil
 }
 
@@ -461,13 +461,13 @@ done:
 		case <-ticker.C:
 			// don't change the order of database flushes
 			if err := s.extraDb.Flush(); err != nil {
-				glog.Fatalf("fatal error: flush extraDb: %v\n", err)
+				glog.Fatalf("fatal error: flush extraDb: %v (Restart your node. We are aware of this issue)\n", err)
 			}
 			if err := s.stateDb.Flush(); err != nil {
-				glog.Fatalf("fatal error: flush stateDb: %v\n", err)
+				glog.Fatalf("fatal error: flush stateDb: %v (Restart your node. We are aware of this issue)\n", err)
 			}
 			if err := s.blockDb.Flush(); err != nil {
-				glog.Fatalf("fatal error: flush blockDb: %v\n", err)
+				glog.Fatalf("fatal error: flush blockDb: %v (Restart your node. We are aware of this issue)\n", err)
 			}
 		case <-s.shutdownChan:
 			break done
diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index 4c7ebe646..577152a21 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -28,7 +28,7 @@ var (
 	errUnknownPeer         = errors.New("peer's unknown or unhealthy")
 	errBadPeer             = errors.New("action from bad peer ignored")
 	errNoPeers             = errors.New("no peers to keep download active")
-	errPendingQueue        = errors.New("pending items in queue")
+	ErrPendingQueue        = errors.New("pending items in queue")
 	ErrTimeout             = errors.New("timeout")
 	errEmptyHashSet        = errors.New("empty hash set by peer")
 	errPeersUnavailable    = errors.New("no peers available or all peers tried for block download process")
@@ -129,7 +129,7 @@ func (d *Downloader) Synchronise(id string, hash common.Hash) error {
 
 	// Abort if the queue still contains some leftover data
 	if _, cached := d.queue.Size(); cached > 0 && d.queue.GetHeadBlock() != nil {
-		return errPendingQueue
+		return ErrPendingQueue
 	}
 	// Reset the queue and peer set to clean any internal leftover state
 	d.queue.Reset()
diff --git a/eth/sync.go b/eth/sync.go
index d955eaa50..00b571782 100644
--- a/eth/sync.go
+++ b/eth/sync.go
@@ -98,7 +98,8 @@ func (pm *ProtocolManager) synchronise(peer *peer) {
 	case downloader.ErrTimeout:
 		glog.V(logger.Debug).Infof("Removing peer %v due to sync timeout", peer.id)
 		pm.removePeer(peer)
-
+	case downloader.ErrPendingQueue:
+		glog.V(logger.Debug).Infoln("Synchronisation aborted:", err)
 	default:
 		glog.V(logger.Warn).Infof("Synchronisation failed: %v", err)
 	}
diff --git a/miner/agent.go b/miner/agent.go
index b2f89aaab..939f63fef 100644
--- a/miner/agent.go
+++ b/miner/agent.go
@@ -10,7 +10,7 @@ import (
 	"github.com/ethereum/go-ethereum/pow"
 )
 
-type CpuMiner struct {
+type CpuAgent struct {
 	chMu          sync.Mutex
 	c             chan *types.Block
 	quit          chan struct{}
@@ -21,8 +21,8 @@ type CpuMiner struct {
 	pow   pow.PoW
 }
 
-func NewCpuMiner(index int, pow pow.PoW) *CpuMiner {
-	miner := &CpuMiner{
+func NewCpuAgent(index int, pow pow.PoW) *CpuAgent {
+	miner := &CpuAgent{
 		pow:   pow,
 		index: index,
 	}
@@ -30,16 +30,16 @@ func NewCpuMiner(index int, pow pow.PoW) *CpuMiner {
 	return miner
 }
 
-func (self *CpuMiner) Work() chan<- *types.Block          { return self.c }
-func (self *CpuMiner) Pow() pow.PoW                       { return self.pow }
-func (self *CpuMiner) SetReturnCh(ch chan<- *types.Block) { self.returnCh = ch }
+func (self *CpuAgent) Work() chan<- *types.Block          { return self.c }
+func (self *CpuAgent) Pow() pow.PoW                       { return self.pow }
+func (self *CpuAgent) SetReturnCh(ch chan<- *types.Block) { self.returnCh = ch }
 
-func (self *CpuMiner) Stop() {
+func (self *CpuAgent) Stop() {
 	close(self.quit)
 	close(self.quitCurrentOp)
 }
 
-func (self *CpuMiner) Start() {
+func (self *CpuAgent) Start() {
 	self.quit = make(chan struct{})
 	self.quitCurrentOp = make(chan struct{}, 1)
 	self.c = make(chan *types.Block, 1)
@@ -47,7 +47,7 @@ func (self *CpuMiner) Start() {
 	go self.update()
 }
 
-func (self *CpuMiner) update() {
+func (self *CpuAgent) update() {
 out:
 	for {
 		select {
@@ -76,7 +76,7 @@ done:
 	}
 }
 
-func (self *CpuMiner) mine(block *types.Block) {
+func (self *CpuAgent) mine(block *types.Block) {
 	glog.V(logger.Debug).Infof("(re)started agent[%d]. mining...\n", self.index)
 
 	// Reset the channel
@@ -95,6 +95,6 @@ func (self *CpuMiner) mine(block *types.Block) {
 	}
 }
 
-func (self *CpuMiner) GetHashRate() int64 {
+func (self *CpuAgent) GetHashRate() int64 {
 	return self.pow.GetHashrate()
 }
diff --git a/miner/miner.go b/miner/miner.go
index efe6d3051..09342e250 100644
--- a/miner/miner.go
+++ b/miner/miner.go
@@ -23,16 +23,8 @@ type Miner struct {
 	pow     pow.PoW
 }
 
-func New(eth core.Backend, pow pow.PoW, minerThreads int) *Miner {
-	// note: minerThreads is currently ignored because
-	// ethash is not thread safe.
-	miner := &Miner{eth: eth, pow: pow, worker: newWorker(common.Address{}, eth)}
-	for i := 0; i < minerThreads; i++ {
-		miner.worker.register(NewCpuMiner(i, pow))
-	}
-	miner.threads = minerThreads
-
-	return miner
+func New(eth core.Backend, pow pow.PoW) *Miner {
+	return &Miner{eth: eth, pow: pow, worker: newWorker(common.Address{}, eth)}
 }
 
 func (self *Miner) Mining() bool {
@@ -48,15 +40,27 @@ func (m *Miner) SetGasPrice(price *big.Int) {
 	m.worker.gasPrice = price
 }
 
-func (self *Miner) Start(coinbase common.Address) {
-	glog.V(logger.Info).Infoln("Starting mining operation")
+func (self *Miner) Start(coinbase common.Address, threads int) {
 
 	self.mining = true
+
+	for i := 0; i < threads; i++ {
+		self.worker.register(NewCpuAgent(i, self.pow))
+	}
+	self.threads = threads
+
+	glog.V(logger.Info).Infof("Starting mining operation (CPU=%d TOT=%d)\n", threads, len(self.worker.agents))
+
 	self.worker.coinbase = coinbase
 	self.worker.start()
 	self.worker.commitNewWork()
 }
 
+func (self *Miner) Stop() {
+	self.worker.stop()
+	self.mining = false
+}
+
 func (self *Miner) Register(agent Agent) {
 	if self.mining {
 		agent.Start()
@@ -65,11 +69,6 @@ func (self *Miner) Register(agent Agent) {
 	self.worker.register(agent)
 }
 
-func (self *Miner) Stop() {
-	self.mining = false
-	self.worker.stop()
-}
-
 func (self *Miner) HashRate() int64 {
 	return self.worker.HashRate()
 }
diff --git a/miner/worker.go b/miner/worker.go
index e3dbae717..d801a9839 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -141,7 +141,6 @@ func (self *worker) start() {
 	for _, agent := range self.agents {
 		agent.Start()
 	}
-
 }
 
 func (self *worker) stop() {
@@ -149,10 +148,16 @@ func (self *worker) stop() {
 	defer self.mu.Unlock()
 
 	if atomic.LoadInt32(&self.mining) == 1 {
+		var keep []Agent
 		// stop all agents
 		for _, agent := range self.agents {
 			agent.Stop()
+			// keep all that's not a cpu agent
+			if _, ok := agent.(*CpuAgent); !ok {
+				keep = append(keep, agent)
+			}
 		}
+		self.agents = keep
 	}
 
 	atomic.StoreInt32(&self.mining, 0)
diff --git a/rpc/api.go b/rpc/api.go
index 309c161ad..d53a9917d 100644
--- a/rpc/api.go
+++ b/rpc/api.go
@@ -391,7 +391,7 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		}
 		*reply = NewLogsRes(api.xeth().AllLogs(args.Earliest, args.Latest, args.Skip, args.Max, args.Address, args.Topics))
 	case "eth_getWork":
-		api.xeth().SetMining(true)
+		api.xeth().SetMining(true, 0)
 		*reply = api.xeth().RemoteMining().GetWork()
 	case "eth_submitWork":
 		args := new(SubmitWorkArgs)
diff --git a/xeth/xeth.go b/xeth/xeth.go
index 47b833a34..bf5844770 100644
--- a/xeth/xeth.go
+++ b/xeth/xeth.go
@@ -425,10 +425,10 @@ func (self *XEth) ClientVersion() string {
 	return self.backend.ClientVersion()
 }
 
-func (self *XEth) SetMining(shouldmine bool) bool {
+func (self *XEth) SetMining(shouldmine bool, threads int) bool {
 	ismining := self.backend.IsMining()
 	if shouldmine && !ismining {
-		err := self.backend.StartMining()
+		err := self.backend.StartMining(threads)
 		return err == nil
 	}
 	if ismining && !shouldmine {