Hi,
You most likely have a virus or malware, try running these:-
Verify Window’s Files
1. Go “START”, “RUN” type “CMD” Press “OK” or Boot PC into “safe mode with command prompt”
2. Type sfc /scannow /f (note:- space after sfc)
3. Windows file protection will check your files. Follow any prompts; you may be required to use your XP CD.
4. Re-boot your PC
On-line Virus Scan
Go to one or all of these sites and do an online virus scan.
housecall.trendmicro.com
security.symantec.com
us.mcafee.com/root/mfs/default.asp
Check Malware
Go to
http://www.besttechie.net/tools/mbam-setup.exe
and download and run Malwarebytes' Anti-Malware.
1. Double-click mbam-setup.exe and follow the prompts to install the program.
2. Make sure you put a check in the Update Malwarebytes' Anti-Malware and Launch Malwarebytes' Anti-Malware, then click Finish.
3. If an update is found, let it download and instal.
4. Once the program has loaded, select Perform full scan, then click Scan.
5. When the scan is complete, click OK, then click Show Results to view the results.
6. Make sure that everything is checked, and click Remove Selected.
7. When completed, a log will open.
Check Spyware
Go to
www.safer-networking.org and download and run Spybot
Unsolved 
