Here's spme additional info:

When trying to launch the Office 2003 installer, I get the following
error:

Runtime Error!

Program C:|WINDOWS\system32\msiexec.exe

This application has requested the Runtime to terminate in an unusual
way.

===================

DW wrote:
Can you open Word?

Yes, wprd opens fine.

Had you already configured a mail profile in Outlook, and did it ever work?

Yes, it worked fine up to Saturday, when my computer became infected
with Virus Burst software and other sypyware. I disinfected the
computer, and this problem appears to be the only issue.

Check your workstation's event logs.

What am I looking for?