I have the GOTY edition of UT which installs and plays OK except for one thing.
I am unable to change the graphic settings, it defaults to 640x480 and whenever i try to change it it locks up. Pressing ESC just resets back to default.

My specs are.

Duron 1ghz
512 PC2700 crucial
Geforce 4 Ti4200 128mb
XP Pro
MaxiSound Muse
WD 30gb HD 7200 rpm

Is this a known issue or am I just unlucky. I'm running the 44.03 Detonator at the moment which is pretty up to date.

make sure you have the latest update for UT
I think it's 4.36, you can get it and other stuff from epic's site also make sure you Vid card's drivers are the latest...

Then , once in game, hit the ~ or tab key, then type preferences & hit Enter this brings up advanced options, and change it there...
also look at this tweak guide
http://www.techspot.com/tweaks/ut/print.shtml

good luck

You need help with what

Are you sure it's locked up? I remember mine taking a few minutes before the menu actually came up. Try some patients. If you look away and it does show up, it will time out and go away and you'll think the menu never showed up.