Check the eventvwr (>start, >run, eventvwr + Enter). Look in the application log. Look for errors and warnings from the sources MsiInstaller or MSOffice. Open them up and see what they say. You can post them here if you want.
In cases where I've upgraded people to 2003 or 2007 a lot of times important DWORD values aren't being created by the installer, so you get these strange re-occurring "configuring" or "installing" messages each time a routine process is carried out.
The good thing, in my case, was the application log warnings were very specific and told me what wasn't there in the registry. Once I saw what wasn't being created I just made a .reg file in notepad and imported it to the affected users/machines.
And yeah, uninstalling and reinstalling won't help, as you've found out.
Take a look at the application log in eventvwr and go from there.