The X Window manager isn't working on my desktop. Everything does fine, I log in and then I type startx (or bt4-crystal) and I jut get a blank white screen (same thing happens, when I use Ubuntu live CD, but there I can boot into Safe Graphics Mode, and it's fine... how do I do that in BT?). I tried generating a new xorg.conf file with X -configure but I get the same thing. Here's my Desktops hardware:

Motherboard: Asus P5QC
CPU: Intel Core 2 Quad Q9550
Graphics Card: Diamond ATI Readon 4870 1GB
Monitor: LG Flatron W2252TQ
(I think, this is all that matter for this, no need to post the rest)