this is pretty tough to diagnose w/out seeing the code. but even so, you mentioned it works fine on 1 server but not on the other.
are they really on the same server? just because you have 2 accounts w/ the same hosting company doesnt neccesarily mean its the same server. if they are different, maybe 1 of the servers is running a diff version of php.
or if they are on the same server, maybe even the same hosting account, if 1 is located at
/home/path/to/doc_root/script.php
but the other is
/home/path/to/doc_root/install_2/script.php
it clould cause problems if the script is not written properly, or it is configured improperly. again, hard to tell unless we can see the source code.
it sounds like your using some kind of prewritten script, because this is NOT an error message generated by php:
"Problem: Could not move file into directory, please go back and try again. "
that is an error message generated by the script itself, and gives us no indication of what is wrong other than the fact that it "didnt work"
if you can, post the source code. otherwise it will be very difficult to help you.