ho scaricato php my admin e ho inserito la cartella che contiene tutti i file nella dyrectory root a cui fa riferimento php
quando lancio http://localhost/phpadmin/index.php mi compaiono questi errori

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 90

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 92

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 94

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 96

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 102

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 105

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 108

Notice: Undefined variable: HTTP_USER_AGENT in C:\www\phpadmin\libraries\defines.lib.php on line 111
cannot load MySQL extension,
please check PHP Configuration.

Qualcuno sa dirmi qualcosa???