I've been using WinRAR successfully for quite a while and then all of a sudden none of my .rar .avi files work any more. The message I get is: " The archive is either in unknown format or damaged." I initially thought that it is only new files that are affected but it is all my .avi files. The jpgs etc are unaffected. I've tried WinRAR, WinZip and IZArc, all with the same result. My virus scan with Norton brought up zip. Repairing the files also did not work. Does any one have any ideas? Thx.