Happens on my desktop, too.
I noticed that it happened much more when I had several programs open at the same time while working on icons. I had WinSPMBT, PSP, Mobhack, W.Explorer, ShpEd, and Media Player(background music
) all open at the same time and the flashing was pretty constant.
Of course, it still happens with nothing else open, but not so distractingly.