Download the free tool called "Remove Restrictions Tool (RRT)" at the link below. It's worth a try
Make sure you boot in to Safe Mode to use Remove Restrictions Tool (RRT).
You should update your virus/malware programs definitions and run a virus scan and a malware scan.
Running winXP SP2 in portatil DELL inspiron 6400.
The legend "show hidden files or folders" in the view folder option changed and now it shows only a numer "1". Other options are as always.