Keep Losing Sound With My Sound Blaster Z PCI

I added a Sound Blaster Z PCI to my PC last summer with great success. I got the best sound out of it while playing music and games. Now the sound will drop out for no reason and I then have to reboot my PC to get it back? Since I upgraded my driver this has been a problem. Can I reverse my driver to the last update or do I need to replace this card?
