I've seen something similar before on one of our user's PC's... Does the site that loads up have a title of "Teen sex". Mostly a blue screen with German content?
If so, then it's a takeover of your HOSTS file... In XP, the file is in C:\windows\system32\drivers\etc.
Open it up in notepad/edit and delete all of the entries that end in the same numbers/sites.
You can protect the file in future by setting the file to "Read only"