Im using a USB live image of BT5 with gnome (64bit).

On boot after the Grub screen i end up getting just a white screen with coloured speckles of corruption as it loads and nothing visible thereafter through it.
I even get this corruption when i boot to text mode.

Im using an ATI Radeon HD 3470 series mobile (asus laptop).

Any idea what the cause of this or how to fix it? FWIW backtrack 4 live on USB booted no problems into text and into X without issues so i assume this is some sort of updated driver issue.