my friend’s comp hasd avast 4.6 (home) & no net connection.His comp was infected with win32 brontok.I tried to update it to 4.7 with setup that i had but failed to do so as the window used to shut down.Also it did not detect the virus during boot time scanning(4.6).
However, at another friend’s house who had expired norton 2005, infected with the same virus I could install avast 4.7 and delete the virus.Why is it so…also no virus cleaner is available for ALL varieties of win brontok.
Are you asking why newer version has better detection than an old one? Well, that’s why we release new versions, don’t we… 
New versions usually have better unpacking support (and some bugs fixed), so yes, they can detect more. Besides, 4.6 is very old these days… it certainly should be updated.
Apart from the fact that brontok is one of the fastest at producing variants so it may not be possible to have a tool that will remove them all.
As Igor mentions the latest version is going to be better, but installing an update on an already infected system might not work. You could have started with loading the latest VPS file, avast! VPS Update - Manual Download copy to USB or CD. That may have had the latest or most recent signatures that may have included the brontok variant. If it cleared out the infection you could then install 4.7.
How did they manage to get infected by brontok without being connected to the internet ?
Perhaps a review of their security practices is in order.
Have you tried a google search for brontok removal tool, http://www.google.com/search?q=brontok+removal+tool, which returns many hits.
some doubts about avast...In this case, the fault isn't with avast! but with the user who doesn't keep his protection updated even though it's totally FREE. :o
The one with norton 2005 had no net…and the guy with avast 4.6 had net but avast did not update.
Also I tried google search but most are for brontok A and one for all variants was just a note…
Are you saying that avast couldn’t be update or the guy does not update avast because he does not want to?
Did you install avast in the same computer at the same time? They will conflict… :