invalid page fault in explorer--repeated

explorer caused an invalid page fault in module exlorer.exe at 167:00401f31
encountered when starting -- loads only wallpaper, no taskbar or icons

Compaq
Win98SE
whatever version of IE comes with it(5.0, I think)

Why would a computer work more or less fine for 5 yrs. and then encounter
this error twice in less than 3 mo.? Probably a coincidence or should I
suspect starting to fail hardware or something?
I fixed this error 2-3 months ago by running the restore disk. (That time
the computer had various other problems also.) This time I'm looking for a
way to avoid needing such a drastic step. Intending to try a repair of IE
and various other possible fixes found via usenet Google & MS KB. After a
virus scan just to be sure. Most of the stuff I googled had no reply as to
whether suggested remedy fixed problem. I *will* let you know how this
turns out.
If nothing else works, would an over-install with IE5.0 downloaded from
evolt.org be a possible fix? Is there any way to be certain it really is
5.0? I doubt I can get into IE to check.
Would upgrading to IE 5.5 prevent problem in future (or fix now)?
This is *not my computer* but he says he had not installed anything just
before problem began, just reading email. In fact the printer, Camedia, and
Callwave are the only things I know of added after the restore.
Any insight much appreciated, even if you can't answer all the questions.

Thanks,
C-C Mom