I have just found the solution to this problem after spending hours trawling the net so I hope this helps you.
make a blank file called test.php and just put the following code into it
<?php phpinfo(); ?>
Now check to see where your upload_tmp_dir is pointing to. I had the problem of it saying not defined. So I created one in the C:/intepub/wwwroot called uploads and then opened my php.ini file and changed the following line
upload_tmp_dir = “C:\Inetpub\wwwroot\uploads”
*remember to uncomment it
Then apply the permissions to full in the security tab. Since then it has worked fine
