Just use 12.1. It's the last ocl driver for xp. Sdk 2.1 or use the one with 12.1. CPU bug should be gone.
I have tried 12.1 and it doesn't help.. It doesn't seem to matter what drivers and SDK I use, both the CPU-bug and fluctuating hash rate remain.. And I've tried many different drivers and SDK's now..
Does anyone have any other idea of what could be causing my problems?