Although this issue has been resolved with vSphere 4 U1, for those of you that haven’t upgraded please be aware of a known issue with Windows 2008 R2 and Windows 7 where the guest operating system can freeze for a long period of time.  The issue is noted in VMware KB 1011709.

The resolution is to either upgrade to U1 or to use the standard SVGA driver and not the one provided in the VMware Tools package.

VMware KB 1011709 Excerpt…

To deselect the SVGA drivers installed with VMware Tools:

When you install VMware Tools, select VMware Tools Custom Install and deselect the SVGA driver.

Alternatively, remove the SVGA driver from the Device Manager after installing VMware Tools.