H,
you probably tried this but... sometimes hardware comes with outdated drivers, so you have to get the very latest from the suppliers web site. In this case:
http://support.amd.com/us/Pages/AMDSupportHub.aspx
They seem to have a tool to online check whether you have the right driver.
As it is crashing in the Open CL driver; disabling the graphips accelerator in vegas might work for you.
Also is your card here:
http://www.sonycreativesoftware.com/vegaspro/gpuacceleration