Turn off Aero for safety.
A new Windows 7 graphics flaw has been exposed that could expose users of the 64-bit OS to experience non-responsive systems, restarts and unauthorized code execution.
Microsoft detailed in Security Advisory 2028859 that the vulnerability is to do with the Canonical Display Driver (cdd.dll), which is used by desktop composition to blend the Windows Graphics Device Interface (GDI) and DirectX drawing, and affects Windows 7 x64, Windows Server 2008 R2 x64, and Windows Server 2008 R2 for Itanium systems.
Microsoft says that there isn't a big worry because code execution would be "very difficult due to memory randomization both in kernel memory and via Address Space Layout Randomization (ASLR)." Still, those who are worried about security can simply disable Aero visual effects to keep this security flaw at bay until Microsoft issues a fix.