Hi,
- Do you see the same user accounts on the login screen?
This issue will occur if there are no proper permissions to delete the files and folders.
I would suggest you to refer to the section “Issue 1: I get an "Access Denied" error message when accessing or working with files and folders” from the following link and take ownership of the files and see if it fixes the issue.
http://support.microsoft.com/kb/2623670/en-us#method11
You may also refer the suggestions provided by Dena B on December 14, 2012 and check if it helps.
Important: Backup the registry: http://support.microsoft.com/kb/322756/en-us
Note: Any data files that are infected may only be cleaned by deleting the
file entirely, which means there is a potential for data loss.
Keep us posted on the status of the issue.