Hello ozna,

What version of avast are you using? Current stable version is 6.0.1000.
Is there any other security software (Norton, McAfee etc.) now and before installing avast?
And, what do you mean “changed Web http port from 80 to 8080”? Are you using proxy, or changing WebSheild’s redirection settings?

Try repair of avast! You can do this by following process:

  1. Go to Control-Panel and open “Add/Remove Programs”
  2. Choose “avast! Free Antivirus” and click “Remove”
  3. Then choose “Repair” and click next.
  4. Reboot your computer.

Thanks.