What is the exact message, and can you select details or is it just locked? I did a bit of internet searching, and found many references to msgsrv32.exe errors, related to C-media sound cards. I makes me wonder if it's a C-media soundcard (if that's what it is) that's built onto your motherboard causing the problems. Can you disable the built-in sound through the BIOS? Probably not, knowing Compaq. I would try taking the X-Gamer out, rebooting in safe-mode (Hit F8, a second before you see "starting windows 98) you may not see this at all on the Compaq, just hammer away on the F8 key until you get to a menu, select option 3 - safe mode.
In safe mode, take a look and see what devices are listed under 'sound,video,game controllers' (right click 'my computer' select properties', device manager) Remove what is listed under that heading ONLY. Reboot, let windows redetect your built in sound. You may need to reboot again. Go do device manager again, under 'sound, video, game controllers', for each device, select properties, and check the checkbox 'disable in this hardware profile'. Go to creative labs, download the latest drivers for the X-Gamer, unzip them into a directory if it's not a self-installer. Shut down, install the X-Gamer card. Power up, when it asks for a the driver disk, either point it to the directory you unzipped them in, or hit cancel and run the setup utility.
Don't know if this will help at all, but it is what I might try.
BTW, if you find you can disable the onboard sound in BIOS.
-Disable it in BIOS
-Reboot in Safe Mode
-Remove all traces of the built-in sound and the X-Gamer from Device Manager
-Reboot, and use the latest drivers from Creative.