Upload issues are usually caused by a problem on the network and just a small glitch in your connection can cause the upload to stall. Error codes 1001-1004 are codes that you will get when there is a network issue.
We have a free Desktop application that makes sending files a breeze, and that will give you a faster upload time compared to a browser. This also has built in functionality to auto-resume if an upload stalls for any reason. You can download YouSendIt Express here. Please try this out to see if it solves your problems.
The failure could also be a issue with your network speed. If you are still having issues, please run a quick speed test to confirm your internet connection? Just click on this link and a speed test to San Jose will begin automatically.
You will normally want at least a 1.0Mbps upload connection to ensure a smooth file transfer.
One last thing that can cause issues is if you are on a wireless connection. Wireless connections are known to have small connection glitches which can cause a file stall and we suggest switching over to a wired connection.