One thing I have come across that sounds similar is an issue relating to access rights, being applied to items in the all users account using the access rights for the user who originally installed the application.
I have only experienced this in a networked environment and with multiple users, sounds like you have a stand alone single user installation so it could be that the symptoms are a little different.
-------- Instructions --------
Check you can view all files and hidden files
Check simple file sharing is off in the view options of windows explorer
Go to "C:\Documents and Settings\All Users" and give all users full access and refresh the security options and untick inheritable permissions and tick reset permissions on all child objects.
Then under the ownership tab make sure the owner is set to include the administrators group and if the local user is not in the administrators group add the local user to the owner list and tick the replace owner on subcontainers and objects box.
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