Re: Question about GtkRadiant
It's not your system. There could be a couple things wrong... when I first started mapping, I used qeradiant rather than gtkradiant (qeradiant is the tool released by Id) and I had mega-issues. Like 1fps (less, actually), light problems, all kinds of stuff. I fixed that by switching over to gtkradiant.
My first suggestion would be to try a different version of gtkradiant. Either a newer one, if there is one, or an older one.
If that doesn't work, it's possible there's something wrong with quake. Maybe try defragging, then ripping all of quake out and reinstalling it with the point release.
Hmmm...I wouldn't go that far quite yet, though. You say quake crashes when you try to play the map? Do you have it set to automatically launch quake on a map compile? You can try switching that off, then loading the map manually through the console. If it still crashes, post the errors here (if you get any errors) so I can take a look at it. If you need any help with how to do any of this, just ask.