Hi,
I dont know what method you are using to upload, but have you tried their own
RapidShare Manager 2 (RSM2)
I wonder if it has a better success rate as its there own software?
As an alternative filehost, Fileserve.com seems to be a big hit with uploaders/downloaders ( including their free members ) but at the moment they are making massive site changes to make their service even better, so they said to expect temporary difficulties.
Filesonic links are all over the net, but, they are getting a bad press because downloading from them is problematic at times.
HF are banning uploaders accounts.
Good luck in finding a more suitable/reliable host.