I will say that anytime I download anything from the server it is a .rar file. I personally use 7-Zip to open all of that stuff, and it works great. Best of all it is free. That is the only thing I can think of after reading this post that may be causing the invalid file type. Cause you should be able to unzip it, and then get a .exe file which is a known file type.. As far as an anti-virus deleting the file it would just instantly do it, and give you a pop up saying that it deleted a file that it thought was a threat. Norton does that to me all the time with the Flight1 stuff. I would try 7-Zip though if you haven't already as it sounds like there is some sort of unpackaging issue. If the file wasn't finished downloading/corrupted it wouldn't let you unzip it at all. Unfinished downloads usually don't even show up as their normal file type. On my system they stay as a blank file or sorts if they aren't automatically deleted by Windows.