Your problem was MultiMiner. I had this same problem a few weeks back. There's a bug in bfgminer so that every time the network difficulty changes (pool switches coins) the hashrate drops.
Yeh, It's a shame because I wanted to give it a chance, I liked the fact its got an iOS app, I would pay handsomely for a CGMiner app on my phone, CGRemote is fine and all that but I need to view the rig from a handset.