IIS 7.5 500 Error with Large File Uploads

I'm having some trouble with a php upload scr开发者_运维百科ipt when trying to upload large files ( > 9-10Mb). The problem I'm running into can be seen on the screenshot here:

http://thecreativefloor.com/capture.jpg

I've changed all the usual areas (php ini settings, web.config settings, although I've posted them below for reference) but this one now has me stumped (and if it was one of those areas I am guessing it wouldn't be showing a 500 error anyway).

I think it has to be due to some problem in IIS, or maybe a script timeout. The script works for anything else below 9Mb, just once I go above that it crashes.

Any help much appreciated

Nick

PHP ini settings:

memory_limit = 256M

post_max_size = 800M

upload_max_filesize = 800M

Web.config addition:

    <security>
        <requestFiltering>
            <requestLimits maxAllowedContentLength="524288000"/>
        </requestFiltering>
    </security>

You might wanna look into this web.config setting, although it might only be applicable for ASP.NET:

<httpRuntime maxRequestLength="16384" />

http://msdn.microsoft.com/en-us/library/e1f13641%28v=vs.71%29.aspx