Confrontation with Vaylin

I've come to the part where my Jedi Shadow confronts and fights Vaylin on the Gravestone. My companion dies, then I die and the game is glitched. It does not progress any further. Vaylin stands there at half health, while I strike at her, the lightning circles go around and around, and my resurrected companion heals me when I'm damaged by the lightning. Eventually, the lightning circles fade out one by one and nothing further happens. I can strike at Vaylin all I want, but, she takes no damage. What can I do? This seems to be a glitch, but, I can find no reference to it anywhere.