decompression bomb

how to delete decompression bomb …an error occours while deleting or repairing…using windows7 ultimate

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)

I’d suggest to ignore these files.
But you can run a boot time scanning to remove files in use.