FastCGI Process error when enable cURL

I have:

windows Server 2003 - IIS 7.0 - PHP 5.2

Now I tried to install cURL. I get the php_curl.dll in the php.ini and have the right extension path. I also added the both needed dll-files to the system32 directory.

Poorly as soon as I activate the extension=php_curl.dll line, I get an internal error 500 with Fast-CGI cannot be loaded correctly.

When I comment the extension=php_curl.dll line out, it works fine.

Any ideas?

I found this in the error log from windows events:

Fehlerhafte Anwendung php-cgi.exe, 
Version 5.2.13.13, 
Zeitstempel 0x4b853880, 
fehlerhaftes Modul php-cgi.exe, 
Version 5.2.13.13, 
Zeitstempel 0x4b853880, 
Ausnahmecode 0xc0000005, 
Fehleroffset 0x0000191a, 
Prozess-ID 0xf21c, 
Anwendungsstartzeit 01cb29beb76560b4.

Try executing it from the command line (PHP that is). My guess is the curl lib that you are referencing is either out of date, invalid or compiled for a different version of PHP...

Open cmd.exe, navigate to the php binary directory, type php.exe -v