The Microsoft Installer Cleanup Utility you find with a search engine can remove that pending install. This is not an offer to write a tutorial or step by step but this tool is what I use to remove the pending install.
If the tool is too hard to use, just make a note of it for your support staff so they can make quick work of the issue.
This is related to the MSOCache and Office 2003. I do not have MS Office, so no CD to re-install. There is a trial version HP put on my computer and that has a repair application. I try to use it and it says "another installation is already in progress". I follow that and the installer cannot find the MSOCache. It gives a very long path: 'C:\MSOCache\All Users\90000409-6000-11DE3-8CFE-0150048383C9\STD11N.MSI' CANNOT BE FOUND. Verify you have access to this location and try again. I am on a merry-go-round. Microsoft's website on this is technically above my ability to fix.