compression bomb?

i just scanned my computer right before i went to work today and the last line of unreadable files said ‘could not delete. this file is a decompression bomb’. what does this exactly mean? i tried to delete it but it wouldnt delete. the file is on my backup drive for my laptop and it doesnt show up when i go to the drive. the file is d:\preload\base11.wim_aza9f4d2fd…and many more numbers and letters

Read more about “decompression bomb” in this thread:

http://forum.avast.com/index.php?topic=32554.0