Uploading a 100 MB file through HTTP is sure to take a long time. Downloading a 100 MB is bad enough, but most people have a MUCH lower upload bandwidth than they do a download one. Chances are most likely that the web server you're working on times out HTTP connections after a certain period of time (my version of Apache has a default 300 second limit). If you're using Apache, you can change this timeoput limit so that the upload won't be cancelled, but I can't imagine the number of minutes or hours a 100 MB upload would take. I'd definitely look for another approach to this.