Joomla 3.2.1 FastCGI Error

Migrated a Joomla-Website from 1.5 to 3.2.1. Worked well so far -> can change Menues, Articles an Template and save it. But, as son as a want to save changes under configuration -> Site/System/Server i will get the following Error:

FastCGI Error
The FastCGI Handler was unable to process the request.
Error Details:
•Error Number: 13 (0x8007000d).
•Error Description: The data is invalid.
HTTP Error 500 - Server Error.
Internet Information Services (IIS)

Does anybody know why.

Seems like your server does not like your new Joomla folders' right-rules (777, 755 etc). Check System -> System Information -> Directory permissions.
If there are any reds- check rights.
It's common IIS - FastCGI problem you know.
If this will not help then proceed here and look at green post.