Description of problem:
When switching between min and max CPU frequencies with speedstep-ich,
the system/X server hangs and I am forced to reboot/poweroff the
system manually. Unfortunately, nothing was found to be logged. I am
running FC2 on a Dell Inspiron 5150 with P4 3Ghz (Northwood) and
Mobility Radeon 9000 video card.  This occurs when trying to set the
speed manually and through cpuspeed.

Version-Release number of selected component (if applicable):
kernel-2.6.7-1.494.2.2
kernel-utils-2.4-9.1.131
xorg-x11-6.7.0-5

How reproducible:
Always

Steps to Reproduce:
1. Boot kernel (speedstep-ich built-in by default).

2. Output from /sys/devices/system/cpu/cpu0/cpufreq/*:
        cpuinfo_cur_freq: 1599960
        cpuinfo_max_freq: 3066590
        cpuinfo_min_freq: 1599960
        scaling_available_frequencies: 3066590 1599960
        scaling_available_governors: userspace performance
        scaling_cur_freq: 1599960
        scaling_driver: speedstep-ich
        scaling_governor: userspace
        scaling_max_freq: 3066590
        scaling_min_freq: 1599960
        scaling_setspeed: 1599960

3. $echo 3066590 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
     $echo 1599960 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
     or,
     $killall -SIGUSR1 cpuspeed
     $killall -SIGUSR2 cpuspeed

Actual results:
System becomes unresponsive.

Expected results:
cpu frequency switches between min and max speeds.

Additional info:
Attached dmesg output.