Comment 11 for bug 366587

I may have the solution to this issue

Disable the legacy bios setting "memory hole 15 to 16Mb"

For some reason my new ASUS P5QC had it enabled. I could not boot the 2.6.28-15-generic kernel on a Ubuntu system just upgraded from 8.04LTS > 8.10 > 9.04

 Disabling the "memory hole 15 to 16Mb" setting solved the problem on this system. Interestingly enough even through I could boot the older Kernel I could not use the CPU frequency adjustment tool untill after I disabled the memory hole setting.

Now all works fine..