Office 2003 on Windows XP.

I have a user that uses MS-Excel heavily and has many custom macros that he
has been using for several years without issue. He uses a laptop that did not
have any issues until recently, he had problems with his battery. This in
turn was determined to be some other internal electrical problem so a new,
identical laptop was reloaded for him from scratch using the identical setup.
Even the same person loaded his new laptop that loaded his old one.

Now every few days this user's Excel will lock up and he has to restart but
when he does so, it restarts in "Safe" mode. We have a solid and current fire
wall and antivirus system. User operates on a network. This issue ONLY OCCURS
when using MS-EXCEL. His VBA is pretty basic stuff, i.e. no API calls or
anything that appears to be causing this problem.

Any ideas out there as to what could be causing this issue? Anyone else
experience this? If so, how was it resolved?

Thanks much in advance for your assistance.