Office SP3 Update Problem/Error

[Tony S.]

I updated Office XP Professional to SP3 and installed the
security patches. Now when I check for updates I receive
the following error:

Office Update is unable to check for updates

The Office Update site is unable to check for updates on
this computer. This may be happening because of one of the
following reasons:

- You do not have administrative privileges for this
computer.
- There is a network problem and the detection catalog
used by the Office Update site failed to download. Go back
to the Downloads home page and try running detection
again.
- Windows Installer patch files (.MSP files) from
previously applied Office updates are missing from the
\Windows\Installer hidden directory on your computer. MSP
files are stored on your computer after update
installation completes because they need to be referenced
for future update operations. If the files are missing you
will not be able to apply Office updates. You may also be
unable to uninstall Office products as a result of the
same problem. Please contact Microsoft Product Support
Services for assistance.
- You installed Office updates in the past and then
upgraded from Windows Installer version 1.0 to Windows
Installer version 1.1. For more information see the KB
article Windows Installer May Prompt for Install Source if
Unavailable.

I can rule out the first and last option but can't resolve
the 2d or 3rd. Any ideas?

Tony S.