I've been using Bootcamp for Sony Vegas Video and Audio programs flawlessly since I switched to Mac about 6 months ago. Now suddenly when I go to boot to Windows, the screen goes blank upon reboot and I get repeating of 3 loud beeps. Alt/Option won't get me back to OSx so I have to turn off machine a few times to get the Mac reboot. All Windows files still appear in Finder on Mac side. What gives?