While running the "Configuration Wizard" I encountered another problem.
"Exception - Failed to create the configuration database. An exception of type System.Security.Cryptography.CryptographicException was thrown. Additional exception information: The data is invalid."
Not that good, but also not that hard to fix.
The first thing you can try is: Go to "%commonfiles%\Microsoft Shared\Webserver Extensions" and check the folder "14". Right-click on it, select properties and then click on the security tab. There you have to give the account "NETWORK SERVICE" full access.
If that didn't not help, you can try another solution: Open your registry, go to "HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Shared Tools/Web Server Extensions/14.0/Secure/FarmAdmin" and remove the registry entry there.
One time, the first solution fixed my problem, another time I needed both.