Hotfix available for Windows 7 RC x86 - read for more info

http://support.microsoft.com/kb/970789

Microsoft KB970789 said:

A folder that is created under the root of the system drive is missing entries in its security descriptor, which may cause some application failures on the English version of Windows 7 Release Candidate 32-bit Ultimate

Click to expand...

If you're running the x86 edition of the Release Candidate, hit Windows Update and get it covered. Not sure when this was "released" but it's today meaning May 7th, just not sure what specific time, I just noticed it myself.

Read the info on the support page to see if it's related to problems you may be having, and get it installed so you're covered just in case...

Now that I think about it, this COULD BE THE REASON why some people installing applications (namely games it seems) in the root directory of the system partition could be experiencing issues with constant UAC prompts. It could be related and it could be the fix, so take note of this. It's directly related to security descriptors... that's what would trigger UAC prompts on some stuff, spot on.