>Haven't used it but it looks as if Winzip isn't helping too much on errors: http://kb.winzip.com/kb/entry/168/

Even if there would be, the wzzip line is where the crash occurs. So, this is where the problem is.

>Have you looked at the new ZipArchive class in Net 4.5 : http://msdn.microsoft.com/en-us/library/system.io.compression.ziparchive(v=vs.110)

Haven't had the time to look at it yet. There are weeks of work behind what is there now and before switching to something else, we need to make sure there wouldn't be any other alternatives.