Basic Problem, Can't Fix ("no playback device available")

I don't believe msblast would effect your sound but getting rid of it might. I would go to device manager and delete the driver, reboot..and let found new hardware wizard reinstall.

then go to Control Panel and check to see if you have AC97 as you sound device.

Try finding the driver online or finding a different way to u=install the driver. If I got around this problem, you can. I promise ;-)