Freezing playback

For some reason on playback while editing in cubase 6.5 the entire program Froze and stopped working. I had to reboot to make it operate again. Is there any suggestions of what I may be able to do ? Thanks
Win 7 PRO
16g Ram
1T Harddrive
700 W Power supply
I /5 quad core Processor
intel Mother Board

Is it working ok now? Then do nothing & assume it’s a odd glitch?

If it’s repeatedly crashing then you need to give more details.