Windows 7: Desktop Icons changed to Default

I just booted my computer and it seems that IE8 icon and the MS Security Essentials icon went to a default icon. Have no idea why. Scanned for virus and malware. All clean.
I had to select another icon other than the original then back to the original to get them back to normal. I know about F5 that refreshes the icon s but it didn't work.
All is back to normal but I was interested in hearing if anyone else had a similiar issue.

Which icon did you select?

IE8 I selected another one from its group with a white background then back to the one with a clear background.

MSE I had to find another one as it only had one in its group. Whatever it was it worked then I went back and selected the original one.

Seems like the icon cache was corrupter and needed to be refreshed.