Usually freezes/lockups like this are caused by faulty hardware, bad drivers or if its an onboard item (video, sound, LAN, etc) possible BIOS issues. If your soundcard is onboard the mainboard, make sure you have the latest BIOS for the mainboard installed, double check the BIOS settings for the soundcard, disable it in the BIOS and find a cheap add-in soundcard card and try that.
Thanks for the input---I had already disabled the onboard soundcard, but after reading your post, decided to reinable it and in set it up in yast(well, i did the opposite of what you suggested). So i removed from yast my soundblaster card. Well, things seem to be working now--no crashes. So must be something wrong with my soundblaster card. Anyway, thanks again. Cheers Chip