Comment 34 for bug 35213

Note that the kernel parameters set by "laptop_mode stop" are exactly the kernel defaults, so that shouldn't make any difference. Also, I'm sure that no action is taken in the kernel as a result of changing those settings to the same values that they were already at.

Anyway, it may be the hdparm settings, the readahead settings or the remounts that screw things up. Could you try changing the following values in laptop-mode.conf to "0", one by one, trying if it still fails after each one:

CONTROL_READAHEAD
CONTROL_HD_POWERMGMT
CONTROL_HD_WRITECACHE
CONTROL_HD_IDLE_TIMEOUT
CONTROL_MOUNT_OPTIONS

That should yield a very clear picture of what the cause is!