is F1, F2, F3, F4, F5, F6
Now depending how it is all set up it is probably going to be F1 or F2. this will bring you to a virtual terminal, it will display a logon prompt, logon as root, and then on the command prompt type 'telinit 3'
It will then say something like 'INIT: switching to runlevel: 3'
And may be a few other lines.
After that you should be back at the command prompt. There type 'xorgconfig' and follow the questions
I suggest you read something like this http://freshmeat.net/redir/rute/9186/url_homepage/rute.2038bug.com
either before you try this or at least some time soon.