Cannot upload.

[yyahmee]

Hello,
I am the owner of a hosting site.
One of my customers emailed us about this script not working.
They told me to let them use copy() but it's already enabled.
I asked the customer more about it and told me that they are having upload problems and want us to figure it out.
Obviously I can't do that.
Could you help us?
The customer told me that he/she can upload but the files stay in temp folder.
When he/she uploads it gives them:
Your Download-Link:
http://www.customeraddress.com/download.php?id=
Your Delete-Link:
http://www.customeraddress.com/delete.php?id=
The customer is telling me it's our server's problem.
What could be the problem with it?
Thanks,
Yudai Yamagishi