Windows 7 - aero transparency

I would do the old gem of uninstalling the drivers, rebooting into safe mode and then running Driver Sweeper.

Once you have done that reboot and do a fresh install of the drivers and see if that has done anything to help matters.

Have you had a look at Windows Update, to see if it offers a driver for your GFX card? Maybe it needs a WDDM driver?

Just a thought.

Malwarebytes' Anti-Malware 1.41
Database version: 3260
Windows 6.1.7600
30/11/2009 10:36:12
mbam-log-2009-11-30 (10-36-12).txt
Scan type: Quick Scan
Objects scanned: 91246
Time elapsed: 1 minute(s), 53 second(s)
Memory Processes Infected: 0
Memory Modules Infected: 0
Registry Keys Infected: 0
Registry Values Infected: 0
Registry Data Items Infected: 1
Folders Infected: 0
Files Infected: 1
Memory Processes Infected:
(No malicious items detected)
Memory Modules Infected:
(No malicious items detected)
Registry Keys Infected:
(No malicious items detected)
Registry Values Infected:
(No malicious items detected)
Registry Data Items Infected:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer\NoActiveDesktopChange s (Hijack.DisplayProperties) -> Bad: (1) Good: (0) -> Quarantined and deleted successfully.
Folders Infected:
(No malicious items detected)
Files Infected:
C:\Users\Lee\Local Settings\Temporary Internet Files\Silverlight.exe (Trojan.Agent) -> Quarantined and deleted successfully.