Depending on the speed of your internet and the size of the file, this may be normal behavior.

Does this happen all of the time or just with certain files?
Also, what web mail client are you using?

all the time with googlemail or talktalk - same problem

Try "baggieaggie's" solution above i.e. reset your router. Don't know why it works but as my "uploader problem" message of today says..it worked for me. Regards Notsnarc.

Thanks