I think there may be something to your wife's Mac jealousy hypothesis. My old iBook's hard disk started acting really strange (not booting sometimes, etc.) after I used it for wireless file transfers to my husband's newer and bigger iBook last spring. I think it started it's demise the day after the new iBook came home. I got a few more weeks of tenuous use out of it, mainly to transfer my files onto other media, then it basically died.
Who knew computers could be so sensitive?! ;)

It booted long enough last night to find out what's wrong. "Unresolved kernel trap," i.e., kernel panic. It's a UNIX thing in the Darwinian core of my iBook, and it is resisting all attempts to fix it. I have OS9 on another partition, but it freezes in startup. Booting from CD also freezes. Zapping PRAM, that old standby, does nothing. More obscure startup rituals like CMD-O-F and CMD-S are also getting me nowhere.

This is so un-Mac-like.

I ended up figuring out I was able to get the system to boot when the machine was cool. Once it had been running for a few minutes it would shut down and not re-start. It was also making scary sounding noises.
I ended taking it to a certain large Kyoto computer store as a trade in. I had to leave it with them for an hour while they appraised it and just hoped for the best. When they asked me about the funny noises I just shrugged and gave a non-comittal answer. Got 6 man for it.
Yeah it was a crappy thing to do but it was crappy for the iBook to go belly up 4 months after the warranty expired. Bought another one and it's doing great. I don't commute with it anymore, which is probably a good thing.