Maybe this sounds stupid but what is the meaning of this message:
“The file is a decompression bomb”
it’s not that the file will explode… ??? But how do i understand this sentence, does it mean that will collapse or stop with working, etc. What is the reall meaning of the message? :-[
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)
Decompression bomb is a file that may be rather small, but decompresses to an enormous amount of data (when processed as a packed archive). Such file are not malicious per se, but they may block an antivirus program when it tries to scan them.
This kind of files is rather hard to detect (and avoid) precisely - so, it is possible that there are some false alarms. It’s not a big problem in this case, however - the “decompression bomb” announcement actually means something like “The file has a very high, maybe even suspicious, compression ratio and the AV is not going to scan the archive content”.
I’d suggest to ignore these files.
But you can change values into avast4.ini file to configure how avast should work with these files.
Click ‘Settings’ in my signature for more info 
the "decompression bomb" announcement actually means something like "The file has a very high, maybe even suspicious, compression ratio and the AV is not going to scan the archive content".
Hi Tech, ok i understand now.Thanks for the explanation.Nothing to worry about, just i was not able to understand what is this about.
Anyway thanks again! 
http://www.pcadvisor.co.uk/forums/index.cfm?action=showthread&threadid=245945&forumid=1
also here snowhite(how are the 7 dwarfs behaving!!)
it says to leave alone also!!!
Thanks drhayden1 ( the dwarfs are behaving fine!) ;D
first, i don’t know English very well, so i hope someone understand me…
i read about decompression bomb, i understand it’s not a problem to the PC; but i just scan my PC and i have a Trojan in C/system volume information and that file have some numbers…{181FB16F-FF5F…}and i moved to the chest, but i also have a decompression bomb whit the same numbers like Trojan in the same place and i can’t move it. it’s possible to be a virus?? because avast says that is unable to scan it…what i must do??? ???
Please:
thank you verry much 