VGA Mode Not Support

Hello,

I am trying to install the latest rc1 version of Vista, but unfortunately
everytime it tries to boot from the disc I get an error messge saying "VGA
Mode Not Support".

I am asssuming this is something to do with my ATI Radeon 9550 card. It has
previously worked on beta's of Vista so I am wondering if anybody else is
having problems? Maybe a solution?

Cheers