Can't install programs

 AAAARGH!

I've had my computer for a few years now, and have never had a problem installing a new program.  Usually when you d/l a new application and click on it it automatically installs.  I recently had a virus that killed many of my files.  I had to basically start from scratch and re install Windows Me and all my other programs.  Most programs were no problem... but when I went to install Win Zip, Quicktime, and DivX, I could d/l the programs, but they wouldn't install.  I had an error message when I tried to install Win Zip that said that Win Zip couldn't create a temporary folder, and that it might be due to the fact that I didn't have priveleges to create folders in the temporary folder.  I checked everywhere, but there is no place to set administrator privileges.  When I started my computer in safe mode I had no problem installing the applications.  Does anyone know what could be causing this?  I've also had the occasional temporary file end up on my desktop, which has never happened before.

Any help would be awesome!  Thanks!