I know sometimes site servers have hiccups every now and then, but I haven't ran into too many problems here.

Alternately, did you also check with your ISP? Some providers have bandwidth caps on their service, and more often than not the upload capability is smaller and more bottlenecked than the download. I'd suggest trying to upload the file elsewhere and see if it has problems there too. If that's the case, give your ISP a call and ask them what's going on.