Failure to sleep: induced by directory errors?

It appears that one possible cause of sleep-induced crashes or a failure to sleep is a damaged disk directory, perhaps as a result of running Classic. Frank Bry writes:

"I have a TiBook 667 running OS 10.1.2. Several times a week I put it to sleep and the light does not pulse and the machine heats up like a furnace and the fan comes on. I told by Apple tech support that the problem was directory related. I was instructed to boot from the PB G4 OS X installer and run "Repair Hard Drive" 2 times. There were major problems with the HD directory. He informed me that running Classic creates these directory problems."