Hi,
if your aero has suddenly flashed and then reverted to basic, it’s probably because of one of these reasons:
-you are running an application that isn’t compatible with aero, or the compatibility options are set to disable aero for an app;ication.
-you’ve opened too many programs and run your computer out of memory.
-you’ve changed the “Performance Options” to “Adjust for best performance” under the Advanced system properties, which disabled desktop composition.
-you’ve disabled the Desktop Window Manager service.
-your video card driver can’t work with aero properly.
Type sysdm.cpl into the start menu search or run box, choose the "Advanced" tab and then the "Settings" button under "Performance". Make sure that at least “Enable desktop composition” and “Enable transparent glass” are selected (Or just choose "Best Appearance"), and then go back into the desktop properties and choose the "Windows Aero" theme again (although you really shouldn’t have to do this step)
If that still doesn’t work, close out of all your open applications, and verify that the "Desktop Window Manager service" is running in "Services" under "Control Panel".
If the Aero still doesen't work - try to install the lastest version of your video card driver, or wait for a new version of this driver, maybe after final W7 release Vcard manufacturer will fix this driver problem.
Also as a last suggestion you can try to boot into "clean boot" http://support.microsoft.com/?scid=kb;en-us;929135&x=19&y=12 (this kb for Vista, but its same for W7) or create new user account with the Administrator rights.
Hope this helps :)
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Kala
