speaker problem

I've had my computer for about 6 months now and I've had no problems with the speakers yet. Now, in Windows ME, sound comes out of all but the right front and right rear speakers. I have Creative Labs DTT2500 Dolby Digital Surround Sound Speakers with an SB Live! Platinum. The weird thing is that when I play a DVD the 5.1 Digital Surround sound works perfectly. I've used the new drivers...uninstalled the drivers and started over. I've unplugged the speakers many times also, but nothing works. Windows is set to 5.1 Surround Sound Speakers and so is the Creative Labs Control Panel. Can someone please help me with this? It would be greatly appreciated. Thanks.