When I attempt to download this file, sometimes it only downloads about 700KB (the file is 40MB) then I get the message that the download is complete. If I try to download the file again, it works properly.
The problem seems prevalent in IE, although I've had it happen in Chrome sometimes too.
I have the following code:
<input type="button"
value="Agree to Terms and Download"
onClick="location.href='/downloads/setup.exe';" />
If it matters, this is over a secure connection.
I also tried zipping the file, and had the same issues.
This sounds like a server issue, what server are you using?
I suggest to set up some web monitoring so you get some better statistics on the issue. Maybe that reveals a pattern. Try e. g. with a free account at AlertFox: Monitor file downloads