Office 2007 won't run in user mode anymore

My office 2007 is not working in user mode anymore. It used to run fine until last week and I can't remember having done anything which might affect Office installation.

When I run an Office program Windows installer pops up, then the product starts. After that, again Windows installer pops up and I get a message Windows installer is configuring the product. After a while a message '<program> has not been installed for the current user" pops up and the application terminates. However, if I choose to run the application as administrator, the application runs without Windows installer dialogs.

I tried to set permissions on files and registry keys, remove files and registry keys but none have worked. I also reinstalled twice, of which one time after uninstall I followed the procedures listed in http://support.microsoft.com/?scid=kb;en-us;928218&x=14&y=8 

I'm afraid I'm running out of options.. Any suggestions of things I still can try?

Thanks in advance,
Mariëlla