multibit.
anyone can recommend me a safer wallet ? maybe something with mail confirmation to approve an transaction ?
MultiBit should be fine...... I use it on a Linux machine (with a 30+ character password) - I can't really see how someone could make transactions from your wallet without physical access to your PC or unless it has been compromised in some way..... What OS are you running? And are you sure the payout address wasn't altered somewhere else - ie. on the miner or in your ckpool settings.....