This is the issue of my friends computer.
The specs there is Intel motherboard, ATI Raedon graphics card, 4 GB ram. After some updates including windows and ATI, the issue appeared that the taskbar icons are always hovered, but even for a running window, the thumbnail previews are not being shown. The situation is exactly like as shown here ... 2009-09-15_2316 - JohnSheehan's library
A system restore can fix it, or a repair install. I want to know what is causing it there.
Any ideas please ?
Thanks a lot in advance .