Common problem with SBLive. I got rid of my P.O.S. SBLive just for this reason. On my last mobo I had to disable ACPI in order to get the damn thing to work.
In all honesty if it's a modern mobo with decent onboard sound, and you're just using it for gaming and casual sound use I'd lose the SBLive and go with the onboard. If you don't have an onboard, a good CMedia chipset card sells for $15 mail order. Simplest way to go if you just want to fix this and don't want any aggravation. Unload that SBLive on someone who REALLY wants it.
If you're using your system as an entertainment system and are actually using the features of the SBLive then I can understand why you'd want to keep it, but most people don't need a SPDIF jack or surround special effects.
Random restarts and freezes are caused by a PCI IRQ channel sharing problem (this is NOT the same as an IRQ conflict, there are four PCI IRQ channels labelled A - D and all your PCI and AGP devices must share them). This problem does not affect ISA cards.
This problem is very common with NICs, some PCI sound cards (the SBLive in particular is VERY prone to it) and SCSI controller cards. These cards do NOT like to share a PCI IRQ channel I explain the problem in detail here with a fix:
http://soldcentralfl.com/quakecoop/glfaq5.htm#5_9
Fix usually just involves moving the SBLive to another free slot and see if it behaves.
If you try all the free slots and it doesn't help then it gets more complicated.
Make a note of which slot each card is currently installed in right now. Pull ALL your PCI cards except the video card and boot up. Make sure the system is working okay. If the problem consistently happens when playing a game, then run that game now and make sure it's okay (most games will run just fine without a sound card installed by-the-way).
If the system seems stable shut down and install
ONE CARD AT A TIME. Start with the sound card. If it acts up, move the card to a different slot until it's resolved.
Repeat this process with all the PCI cards starting with the NIC card next if there is one. DO ONE CARD AT A TIME because one of these other cards may conflict with the SBLive.
Have your drivers handy - moving a PCI card usually forces Windows to re-install the drivers.
If you can't resolve the problem this way, your only recourse is to disable ACPI in BIOS but I don't recommend it. You will no longer be able to have Windows turn off your computer for you automatically, and other power saver features may stop working. This change is also somewhat permanent - you'd need to do a repair install of WinXP if you ever enable ACPI again.
Honestly, just lose that SBLive. You'll be MUCH happier.
Hope this helps...
