From the google searches, I read quite a bit just to educate myself to the nature of the problem and seek for solutions. It appears there are LOTS of people have similar problem like mine. Why Microsoft does not come with a fix?

In trying to fix this problem (deleting the INFCACHE.1 file), I had to grant permission the user group (in fact this computer is used only by me); resulting in a slightly different look-and-feel on my screen background (now all black with icon). Before, the background is a picture. How do I switch back to "admin" and get my picture to appear again on the screen? Thanks again.