error – referenced memory can’t be read

I have a W2K Pro ThinkPad user that upon logging in this morning gets the following error after domain authentication but just before the desktop comes up:
Explorer.exe – Application error “The instruction at “0x100179f9” referenced memory at “0x00000030”. The memory could not be ‘read’.

He uses his Domain id and is in “Admin” class of user. If I log in as domain Administrator the desktop comes up normal. Can Explorer.exe be “cut and pasted” back in to replace it, assuming it has the problem? He swears, don’t they all 😉 that it worked fine Friday and he didn’t do anything over the weekend.

Anyone have any ideas before I do anything drastic?

Thanks,
David