Windows 7 Home Premium 64bit Asus laptop: Have had several problems with downloads and updates being reported as corrupted. I can download them on an XP desktop, running Avast with no problems. Today Firefox wouldn't update so I downloaded the update separately on the Win7 laptop. File wouldn't open ...reported corrupt. I turned off avast shields for 10" deleted the corrupt download and downloaded the same update with avast off..this time the download installed with no problems. I updated from avast 7 to 8 and repeated the experiment...same result. Apparently, on some Win7 systems, Avast shields may corrupt downloads.