OK - the Creative Labs SoundBlaster Live! series has a nightmare driver stack which can get corrupted. And once corrupted it is a ROYAL pain to set back up.
If you look on the CDROM that came with the card you will see a 'restore' program, which resets the drivers when corrupted. You must 'explore' the CD to find this program as, thanks to AutoPlay, it will never show it to you itself. You can try that restore program before doing the following (Creative hides that program - it took me days of flakey driver debugging before I saw that little helper!)
This is how I got a very, very flakey Live! to finally keep it's driver stack intact:
(1) Restart Windows in Safe Mode (hold down Control key or hit F8)
(2) Right click on 'My Computer', click on the tab 'Device Manager' and in 'Sound and Game Controllers' remove all Creative Labs devices and the codecs and kernel drivers needed for the sound card (which is pretty much all drivers showing in that section assuming that you do not have other sound or multimedia encoders (like a DVD card)). Remove the Sound Blaster MS-DOS emulation from the Creative section of the Device Manager list. Remove any other components listed for SoundBlaster support (I'm going from memory here so I'm not quite sure if I just told you all the possible locations for them).
(2a) If you have drivers for all other system components handy (in case the computer asks), and want to make sure this is done right, go into the 'System Devices' section and remove all 'IRQ holder for PCI steering' items.
(3) Close the Device Manger and do not reboot. Go into the Control Panel, into Add / Remove Programs and uninstall the SoundBlaster utilities.
(4) Turn off the computer completely and remove the sound card from the system.
(5) Start up the computer. If you did part (2a) it will redetect all IRQ's, some components, and a few drivers.
(6) Continue restarting the computer until it no longer wants to automatically restart itself. Then, shut down the computer completely.
(7) Reinstall the sound card in it's original slot.
(8) Start the computer and install it's drivers.
Good luck (I didn't want to add this, but with the Live!'s you'll need it...)