One of our customers has just found a problem when trying to create a file on the root of the C:\ Drive, on a Windows 7 Professional PC.

I know they shouln't be keeping files here, but there is a valid reason in this case, so I've relaxed the security on the root of C:\ by giving the group 'users' modify permission.

Before I relaxed the security, the user was receiving 'access denied', but now they are receiving the message:

An unexpected error is keeping you from creating the file. If you continue to recieve this error, you can use the error code to search for help with this problem. Error 0x80070522: A required priviledge is not held by the client.

Googling for this suggests that it is caused by UAC, but how can I get round this when the user doesn't have admin rights on their PC?