Application goes grey

This has occurred hundreds of times since I have been using Windows 7 - both home and at work on 4 separate computers.

Every once in a while when in a window (whether it be a browser window or ftp or some other application) the whole window will go gray. Sometimes it comes back and sometimes (as this morning) it didn't come back (was in a telnet emulator window).

Nothing in the event logs.

These forums appear to have some application-specific questions from over a year ago with no difinitive answers other than the usual - upgrade the graphics drivers, etc...

I'm guessing there is a new feature with Windows 7 that turns the window grey under certain circumstances. Any ideas what that new feature is and what it means? It may help others who have been seeing this behavior.

Windows 7 may be detecting a communication problem and "freezing" the window so the user doesn't do too much "damage".

Thanks.

No, UAC always "dims" the entire screen. This is turning an individual window grey.

The cursor is normal for the title bar but the rest of the window shows the standard blue spinning circle Windows 7 wait cursor.

Is it only Telnet windows or other applications? A greyed out window shouldn't occur so often on so many different computers.

It occurs with most applications - telnet clients as well as IE and a few times with Visual Studio 2005. I've had Windows 7 it since it came out so its only been a few a week and mostly its gray for 5-10 seconds at a time, no problem. Rarely the window fails to come back.