My mining rig is also my database server, so I can't have the mining processes consuming 100% of the CPU. Unfortunately, this driver issue is as yet unresolved by AMD.
However, the problem can be
alleviated, though not completely eliminated, if your processor has more than one core. In the screenshot below, you can see my mining processes are very low now. They still fully consume the resources of one core, however.
Furthermore, this action may increase the hashing rate on some systems. In my case, I went from 1.3Ghash/s to 1.5Ghash/s (dual 6990) with this change, because the database server was competing with poclbm.exe for CPU resources.
Here's how:
https://i.imgur.com/c8znu.png