I recently upgraded my mother's computer system -- motherboard, CPU, memory. She has an inexpensive (cheap!) Yamaha sound card that appears to be completely and properly installed, yet it produces no sound whatsoever. Speakers are attached to the proper jack, Device Manager reports no conflicts and Multimedia shows everything to be in order and working. I even installed a new sound card in her system today with the same results, only this time her modem was "disconnected due to hardware error." Again, nothing seemed out of place, no conflicts, etc. It's the first time I've ever seen this and it has every indication of being a resource problem. But it also could be hardware, I don't know. One final thing. The first sound card was an ISA; the second was a PCI. I plugged the speakers into a portable radio and got sound, so I know the speakers are working. No system buzzes or beeps either. Any ideas on this one?