(I’m just a newbie in this forum)
I’ve been using avast for more than a year and I’m really satisfied
with its protection. 
But lately, there were worms “spreading” in the computers in our
dormitory that avast cannot detect. It was easily spread through
flash drives since those worms automatically installs itself on the drive
especially when autorun was turned on.
These are “.vbs” files. I believe they don’t cause any harm. But it is
annoying. >:(
I constantly update my avast but still I cannot detect those worms.
when I tried inserting my flash drive to a pc with antivir AV the worm
was detected and deleted successfully. I don’t want to change my AV
to antivir. Avast is still the best for me. ;D
I hope the avast team will work harder on updates for the virus database. 8)
If you still have those files in question, submit them to avast! team so they can add detection for them.
http://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=199