I found a solution in the php net manual. I have copied it in here, maybe it would help other users to spend less time on it. Thank you for the answers, it helped me to find the solution:
[
dk.php.net]:
Bruce Kirkpatrick
28-Oct-2009 05:48
On Windows Vista or above, an entry in the Windows/System32/drivers/etc/hosts file causes mysql_connect() connections to "localhost" to timeout and never connect. This happens on php 5.3 and above since it now uses mysql native driver which has changed it connection behavior compared to libmysql.dll in previous versions. It is not a PHP bug, but definitely a configuration issue for users on new windows systems.
To get around this, you must remove the entry like this:
::1 localhost
and make sure you still have:
127.0.0.1 localhost
Also, you could change the code to connect to the ip instead, but that is inconvenient if you have many web sites.
This issue occurs on Windows Vista, Windows 7 and Windows Server 2008.
screenshots