Hi Ammar,
you have right about this that your PC is "infected", probably with some version of Fake AV, but don't worry We'll help.
Please follow my next instructions and provide us results, ASAP:
1. Run BitDefender or Panda Online AntiVirus Scan:
http://scforum.info/index.php/topic,734.0.html2. Download & run HijackThis:
http://scforum.info/index.php/topic,785.0.html3. Provide us logs from HijackThis & AntiVirus Online Scan
I'll wait your reply (with logs).
Regards,
Samker
P.S.It'll be also very useful to provide us screenshot of that Warning message.