I have a Eee netbook with Win7.......
Hi, I installed Avast few days ago..........
what AV did you have before you installed avast ? did it come with a preinstalled AV ? have you removed it ? did you run a removal tool to clear any leftovers before installing avast ?

run and reboot - Uninstallers for Security Software
http://thewebatom.net/uninstallers/security-software/