The Windows Installer Cleanup utility may be of some help to you:
http://support.microsoft.com/kb/295823

I've had to use this in the past - kind of scary because you end up having
to reinstall the application. That gave me concern that I would get into some
issue with activation, but it didn't. However, all updates had to be
reapplied. My problem occurred, as it has with others, when cloning from a
small drive to a larger one as an upgrade to the hardware on a system. But
that's a situation not even mentioned in the description of the use for the
Cleanup utility, so I offer it as a possible aid in your current dilemma.
Good luck.

"Peter van der Donk" wrote:

After doing a system restore on a Windows XP Professional SP2 notebook we've
got a dependency problem with installated Office XP Updates.

Office XP is installed through GPO policy. Then updates get installed
through a WSUS policy. After restoring to a earlier time, we've lost a lot of
later installed updates. When starting office Word, Excel of Powerpoint you
get errors that the system wants to install something but can't find it.

I've solved a lot of them by extracting the packages and pointing the
installer to this location. But now have excelff.msp (KB918420) and this one
is really annoying. I keep getting an error that this is not the right
installation package.

Would like to know if there is a way to break through the circle.

PD