Thanks Ken for the reply
Unfortunately I am still having problems with this. It is definitely related to the balanced web server as I set up just a standard linux hosting account and the demo file works fine.
The hosting company insisted it should work fine with just the "/tmp" folder but my tests do not back this up.
This is what I added:
$uploader->TempDirectory="/tmp";
Curious as to how a standard upload script works fine on the balanced server but the php file uploader doesn't.
I may have to move my clients site to a standard server in order to use your script but would prefer to keep it on the balanced server.