Suffering from this god awful Vitro/Virut virus. Have reinstalled my system, and sadly have most of my files on external HD with I think has been infected as well. I’m not up on PC’s and programming really. I checked some of my .EXE’s on my HD with Avast, and it gives a ‘clear’ with the exception of something that couldn’t be scanned. When I see the report, it says something about a .mls I think and ‘Decompression Bomb’. I take it this is a bad thing? Now have I these .EXE’s in a Zip/RAR file on my HD - can this virus weed it’s way into them, or should they be relatively safe?
By examining 1) the reason given by avast! for not being able to scan the files, 2) the location of the files, you can get an idea of what program they relate to. You may need to expand the column headings to see all the text.
Files that can’t be scanned are just that, not an indication they are suspicious/infected, just unable to be scanned.
Also, the packaging of the file could have some error, or use a non-standard pattern…
Decompression bomb is just something that unpacks to an unusually big amount of data even though it’s rather small (i.e. has a high compression ratio, for example). It’s nothing to worry about, you are just informed that avast! will not try to unpack the archive (you may not even know that it’s an archive, but it seems like it is) because it may take VERY long to process.
(quoted from Igor: http://forum.avast.com/index.php?topic=15389.msg131213#msg131213)
Don’t worry.
Thanks Tech! 
I’m glad you reassured me. I did do a search after I posted here, and the consensus was it was pretty harmless. But after this nasty bout with the dang virus, I wasn’t sure?
So as long as Avast doesn’t see a ‘threat’, I should be okay. I’m putting a lot of faith into Avast now, but so far have no complaints. Been very good in what it does. Just wish I knew about this great program BEFORE I got this awful virus. 
Thanks again.
Noisemaker, you’re welcome. Feel free to come back any time you need help or just to change experiences 8)
Hi!
Newbie here! first time poster and might be a regular poster on this forum as I am experiencing problems with my computer slowly booting up. I’m using avast as one of my antivirus the other one is malwarebytes. I also have ccleaner for my registry. I started using ccleaner last week to clean up my registry to be able to boot up my computer faster but instead of achieving what I wanted which is to boot up faster it is much slower that it was before. I scanned my computer on a safemode using malwarebytes and it didn’t find any virus. I scanned it once again using AVAST (it took half a day for the scan to finish) and I got a result saying that there are 4 files that can’t be scan because the file is a decompression bomb. what to do with this files, please help?
Forget the decompression bombs. They aren’t harmful (generally).
Try http://soluto.com to test what is delaying your boot.