Hi Mukesh, I'm not sure what the problem could be, but have you tried getting the latest drivers for your graphics card? Also, sometimes rebooting gets overlooked, so try rebooting your pc, if you haven't yet.
We have seen something similar in that there will be an active small graphics window in the main graphics area. We found this to be mostly caused by the user turning off the Aero crap. Turning it back on has pretty much stopped it.
Yes, that is pretty much what I'm seeing but I don't remember turning off anything named "Aero Crap". How do I turn this on?? I did a search in the help file for this but no match found.