MindedCobr: I tried this on my windows 7 32bit and still doesn´t work ... I get no error, but the game doesn´t start
I may be mistaken, but I think for a 32-bit OS you need to put the file into system32, not system. You should also run the
DirectX End-User Runtime Web Installer (if you haven't already) to ensure you have the latest compatibility fixes.
If you are still using the beta (7000) rather than the Release Candidate (7100) you should back up your data and do a clean install (not an upgrade install) to ensure maximum stability and compatibility. If you did an upgrade install to get to your current version, consider doing a clean install instead. Upgrade installs work well between released versions of Windows but can cause some serious issues on beta/RC versions.
EDIT: you could also try disabling/quitting your security software during installation. Some security programs can interfere with certain installation processes for various reasons, and in the case of games this can lead to the game not working.