word, excel, etc on XP try to install with each use
 

I work for a small non-profit with a bunch of hand me down computers. When I
open Word, the system 'installs' it every time. It's a pain, but I can deal.
Today is the first time I've tried to use Excel, it goes through the same
process but dosen't open and gives Error 1706. I don't have the install
disks, but I do have the product number. Help!!!