Hello,
I had the same problem with most downloads and I ended up with the conclusion that it happens because my network connection is too fast! (warning, this may be wrong as I could not check with a slower one

).
I don't think the file on the server is corrupted, it rather looks like it's not fully downloaded.
However, eventually I managed to download every plane I tried by using one of the following tricks (for reasons that escape me, none worked in every occasion):
1. Start download while something else (the bigger, the better) is transferred via the same network.
2. Select "Run" rather than "Save" option in Internet Explorer (it beats me why

). The tricky part is that if you actually want to save the file, you can find it in the "Temporary Internet Files" folders - but only BEFORE you finish running it, afterwards it's deleted. This was most necessary for me as I'm not using the same PC for FS and downloads.
By the way, these tricks suggest a third one, but I didn't try it (yet): download using another browser.
Hope this helps
Andrei