|It appears you are not on a domain in an office. If you were the system administrator would have made sure your virus protection was up to date.|
The symptom is one I recently had from a customer with a rootkit virus infection. What internet security are you running? How often is it updated? Once the system gets to this state I normally recommend making sure the data is backed up and then wiping the drive and doing a full format and reinstall. You will spend more time than it is worth to try repairing the problem. An XP repair install will not correct this virus problem, it only extends the time you start a fresh install.
The first step if data is not backed up would be to slave the drive to a known clean system after making sure it is updated and protected.
1. Install the drive and immediately run a full/in-depth scan on the drive checking for all problems.
2. Your anti-virus needs to be able to detect rootkits during scan.
3. Offload the essential data files.
4. Reinstall the drive in the original system.
5. Now run the full reinstall of XP and all programs.
This is the quickest way to get back up since you could be looking at hours of scanning and trying repairs and still not be successful.