edit, my Crossfire got enabled automatically when it installed 11.12 I discovered this because Skyrim started playing really funky, and I remembered people talking about funky behavior with Crossfire. So I disabled Crossfire, and my Mhash/sec came up a little bit (although it seemed about par w/out Crossfire, so maybe that's fixed now? someone might do some more experimenting)
and the CPU bug is still fixed for me.
I tried updating to 11.12 on one of my quad radeon hd 5870 windows rigs and it did not fix the 100% cpu bug.