Windows installer

Where is the “staging area” for the windows installer. What I mean by that is when you open a program the Windows installer knows to pop up and ask you to install a program. I have serveral users that are having the same MSI trying to install when they open different programs. The MSI file has nothing to do with the program they are opening. For example SAP.SystemUpdate.msi is trying to install when one user tries to open Word,and it tries to install when another user opens Documentum…

How can I get rid of this?

Thanks,
Bra-k