I have recently come across an issue that became apparent when installing the latest VDA when IE9 is also installed. IE would completely freeze for no rhyme or reason or certain web sites with flash content would cause IE to become unresponsive. After much analysis and late nights I have found that changing the following registry keys on the master image fixes the IE9 freezing/Unresponsive issues.
Delete the following registry key
HKEY_LOCAL_MACHINESoftwareCitrixCtxHookAppInit_DllsHDXMediaStreamForFlashiexplore
Create the following registry key
HKEY_LOCAL_MACHINESoftwareCitrixHDXMediaStreamForFlashServerPseudoserver
Name: DisableInputSyncCallForSetObjectRects
Type: REG_DWORD
Data: 1
Since applying the above I have had no issues with IE9
