Error opening access control editor

Hello,
I am trying to set permissions on a folder. I go into the properties of
the folder and select the security tab, then I click on edit. I get an error
"Cannot open access control editor. Invalid value for registry."

Any help would be appreciated, I am a developer and would not like to
re-install Vista to resolve this issue.

BTW OS is Vista x64 Ultimate

Thanks!!!
-Russell