Outlook XP sends one message many times

Outlook xp sends one message many times and I cant delete
it. It stays in the outbox. when i try to delete it an
eror come up saying "The messaging interace experienced
unknown error ... "
Reinstalling the whole Office doesn't help .

I have 3 PCs with such symptomps for now . OS is WIN98 SE

Looks like the only option is to reinstall everything
starting with OS ...
Any ideas ?