i have a compaq presario, model 5400US, w/ winXP Home, SP2. Sound device is OEM, on the motherboard. SOFTWARE is Soundmax by Analog Devices. When i turn on the machine, i have no sound. control panel-sound devices says i have no audio device. in device manager-sound, soundmax is there, and is set up to use this device. When i uninstall the driver there and REBOOT, i get the found new hardware window. i let it search for the software, and it finds soundmax. i then have normal sound. when i reboot, i am back to no sound. Things i have done: in BIOS, onboard sound is enabled. in device manager, when trying to roll back the driver, it says none are in backup. I have downloaded the up to DATE software, with the same results. I have purchased and tried two different SOUNDCARDS, (Creative & Dynex) with exactly the same results as the onboard device. It is apparently not loading the correct drivers when booting. Any ideas?What happened prior to this? In Control Panel everything looks normal? And the soundcards, when added, had the onboard sound TURNED off? Did they show in Device Manager the same way? Did you uninstall the SoundMax drivers when the soundcards were added?GX_1MAN, to answer your questions in order: yes, yes, yes, yes. thx for your reply.Do you have a LOT of add-on PCI cards in that machine?GX1_MAN---- No. The machine only has three slots. One is a modem card, one is a LAN high speed card, and the last is empty. They were both there long before this problem started.