IIS/PHP File Upload Issues

It is a file upload script and the URL is valid on the server. I've been trying for weeks to resolve this issue and nobody seems to be able to help me locate the problem.
A more detailed description of the problem:
Uploading files larger than 10MB nearly always fail but occasionally they get through. I believe the php.ini file to be setup correctly with the following settings:

C:\Temp\ is writable.
I have tried various scripts and all have the same outcome so I don't believe it to be a coding error. I see the file upload to C:\Temp and when it fails the file remains so it's almost like it just doesn't want to move the file. As I say, occasionally the file gets through and files less than 10MB get through fine so it is unlikely to be a permission issue.
I also changed maxAllowedContentLength in IIS to 30000000 with no success.
I then created an uploader in ASP which worked fine so this indicates its definitely a PHP issue.
I am totally lost with this one and nobody seems to be able to help me get the issue resolved.

 

Just a quick one... have you tried installing Apache along with IIS? I know it may sound weird, but you can actually get these two to work together... its a technology change though.

 

Maybe it's got to do with your FASTCGI settings. I checked and noticed that you can set timeouts there for request, activity and idle. Try increasing those and retest? Inform us if you solve it or not and how.

 

I didn't know you could. I only recently switched to a Windows server.

As per the issues, I don't know what I did but it appears to be functioning correctly now.