Google.com problem

My PC with a freshly installed Windows xp Professional SP3 doesn’t
seem to work well with Google.com and its subdomains like mail.google.com .

When I search I get a bland page with the text “Access to Proxy requires some authentication”
or a messed up search page with different letters.

http://imageshack.us/photo/my-images/27/unledka.jpg/ Search on google.com
http://imageshack.us/photo/my-images/17/search2k.jpg/ Search on google.hu

The first thing I did after installing the drivers and establishing an internet connection was
searching on google, so I highly doubt a virus causes this.

When loading gmail.com I get
"Not Found

The requested URL /accounts/ServiceLogin was not found on this server.
Apache/2.2.3 (CentOS) Server at www.google.com Port 443"

Edit: On another Note : Is BitDefender Internet Security 2011 any good?
I’ve got a free license for a year.