Avast! Provider error

Hey guys. One of our computers is having a problem with avast!. When I initialize the PC, it’s pratically crashed. And avast’s providers didn’t work also. When I uninstalled avast! from it, it was ok. I installed again, with success. After a couple of days, the same problem has ocurred. I tried to Repair the installation, but no success. What could it be?

Please, post the last 200-250 lines of avast log: C:\Program Files\Alwil Software\Avast4\DATA\log\Setup.log

Do you have any other antivirus in this computer?
Had in the past? Which one?