So basically what happens is your browser tells DLP's server it's about to submit a post, the server responds saying ok and gets ready to receive the post. If the server is left waiting too long it will stop waiting and reject the post. It's pretty hard to narrow the problem down, but unless other people chip in and say they're having the same problem I'm inclined to believe the problem is with your setup, or the connection between you and DLP in some way, so some questions:

What is your:
Operating system and verison?
Web browser, and any addons/extensions?
Anti-virus/firewall?
Physical location (America, somewhere in Europe/Asia, wherever)?
ISP?

EDIT: did this begin happening around the time of the Nepal earthquake by any chance?

 

408 is the status code returned by the server when the client does not send the request in a timely manner. Given that you're on Hughesnet, a satellite internet provider, this means your request has to literally travel into space, back down, and then make it to DLP. A lot can go wrong with signals there. DLP returns a 408 to protect its self from attacks designed to tie up resources for extended periods of time.

In addition, if you resend a request without checking if it made it through you can end up with a double-post situation. This happens most often on very unreliable networks (e.g. mobile or satellite networks). You can send a request that makes it through without the client ever knowing it succeeded.

Sorry for your troubles, but there really isn't anything I can do to help. Check with Hughesnet and ensure your satellite is properly aligned. We had satellite tv long ago and we had to recalibrate the dish every so often.