Ok, well, I did some more troubleshooting last night and found out that it is the alarm clock program that is (apparently) causing my problem. I have sound up till the point that the alarm goes off. As soon as the alarm goes off, my sound goes out completely and I have to reboot to get it back. I guess it still could be one of the apps I installed that could have caused the problem. Maybe I just need to find another clock program that will let me set alarms and use that. Any suggestions?