vista 64 installation sent x reboot

Hello. I've searched the posted installation problems and havent seen this one. I downloaded and burned the ISO of vista 64 and installed over my xp pro 64. The installation appeared to be going smoothly when the screen froze reading "Installing Windows" and the computer rebooted. Upon reboot, a gray status bar runs like windows is opening then a blue/green background screen opens with a black command prompt screen reading x:\$WINDOWS.~BT\Windows\system32>
I've tried to boot from the DVD with no luck. I've even tried to boot from my XP 64 DVD and it will not work. It reverts to booting from this x: drive. It wont allow me to access my c: drive (hard drive). It says it does not exist. I think it renamed my hard drive x: Anyway Im stuck at this point and cannot use my computer. Any suggestions?
Thanks.