error attempting intall vista

Downloaded and burned Vista Beta 2. When I restarted and attempted to install got the following Error:
"System Memory manager (EMM386.EXE) has detected an error caused by a fault in one of the devicedrivers or programs loaded in the system. Due to the fault the system is probably in an unstable state and you are therefore recommended to reboot the computer immediately."
Have disabled all start up program but still the same results. Can Anyone suggest a place to start or would I be better off doing a complete "clean" install.