Message erreur première connexion

Having a look at initial print screen , I could see "PHP Warning: PHP Startup: in Unknown on line 0" below message for incorrect login.
This error is send by PHP because some modules sould not be loaded.
So your PHP configuration is not correct.
Check for error in Apache error log file.
This sometimes happen on WAMPSERVER where dll are not adapted to the OS.

So, your php 5.5 installation may not be "completely" correct.
Check for errors in PHP log file and Apache error log file (if relevant).

You must find wich module generates warning "PHP Warning: PHP Startup: in Unknown on line 0", because this means that the module is installed but with wrong DLL, so that when trying to use it, some error (possibly silent) will occur.

If you can, try and install an EasyPHP (at least for a test) as it generally works fine.