I purchased my X3 Producer upgrade two days ago, but I STILL can't fully download the thing! I have parts 2-4 successfully downloaded, but Part 1 keeps finishing its download at 400K+ and reads as a "corrupt" file. I've refreshed the download page and gotten the new links but it's been like my 7th download attempt for Part 1 and it still won't come in complete. Am I the only one with this problem?
 

Some people had a few problems during the first days of the product release, but that's mostly dried up. The only thing I can think of is if your download is particularly slow, a browser might decide to time out leaving you with an incomplete download. If it's still a problem, do contact CW support.

If you are trying to download a huge file with the built in download capability of most browsers, you are likely to have problems. There are several free programs that will make downloading faster and cure many corruption problems.
 
http://www.techsupportalert.com/best-free-download-manager.htm

+1 Definitely get a download manager... many will even allow you to continue a download you have paused (or even disconnected from).

OK, it finally downloaded. I guess persistence (or just airing out my frustration)) works. I was using Firefox to download. Is this Download Manager a 3rd party program?

FireFox has a download manager built-in but I replace it with FDM. It seems to work better for me.