ICURA, I would be surprised if this turned out to be a MSIE6 problem. I did a text search of the MSIE6 newsgroup and in 279 pages of bugs and what-not there was no mention of user.exe. I also did a search of the MS database and there is no document with both "Internet Explorer" and "user.exe" in it.
The Windows module user.exe has been around forever. It is the one that converts user input to monitor output. That is why the error occurs when you move the mouse or scroll.
I'm having trouble imagining why this particular problem might be an incompatibility between different applications.
Have you looked at the PC manufacturer's website to see if you have the most current drivers? (Or patches for the most current drivers?)
If you keep a lot of Windows open, especially of applications that greedily consume system resources, then it is possible that the problem lies there. (You'll find a resource meter in the windows directory.) I have it at the back of my mind that Office is not a problem unless you have enabled a font preview option and have a lot of fonts. Do the problems occur only when Office is open and is this option enabled? (I took MS products off my machine as soon as I got it, so I don't know for sure. This thing about the fonts preview is something that I think I read but may not have remembered accurately.) I'd start with the drivers.