nondeterministic device probing (mouse, laptop)

Hi all,

My laptop (ThinkPad T400) is running 8-current from May 24 or so.

Sometimes, it fails to probe /dev/psm on boot; if I turn it
off and turn it on again, it usually does find the mouse the second time.
Any thoughts for how to start debugging this?  I don't even
know whether to suspect hardware or software more, at this point.

Thanks,

Ben Kaduk