Comment 56 for bug 36014

Arthur, it appears that this bug shows up somewhat randomly, and is not necessarily reproducible even with the same hardware and software configurations. I had the bug for months, and then it went away without explanation. Others have it even with newer kernels.

Mirco, you should look at scaling_max_freq, scaling_min_freq, cpufreq_max_freq and cpufreq_min_freq, all in /sys/devices/system/cpu/cpu0/cpufreq. If scaling_max_freq is not the same as scaling_min_freq, then you are not experiencing this bug, and have another issue. If you do have this bug, then you might want to try my suggestion detailed in previous comments about commenting out the PPC frequency limiting code if you are comfortable with doing so.