My Win2kP will keeps on restarting when it detecting some new USB device but not all, and it never keep me a chance to use it... Did anyone know how to stop it from auto restart at after hw detection? Same pc with another partition of Win98 didn't have this problem and same USB device. My true headache in the restart problem in detecting external USB harddisk and Casio QV4000 camera.

Did the Casio say that you have to install the driver for it? More camera these days do not need drivers installed for them; Windows ME and 2000 on up is supposed to detect the camera as a mass storage device and come up as just another drive in Explorer. The driver for the camera may be interfereing with this function.

I had to fix this once, but I do not remember the details. Try going to device manager and uninstall the driver. Reboot, and hopefully instead of reinstalling the driver by itself, it will give you prompts to choose a location. I think you had to select the System32 folder, and from there I cannot remember much. What your objective is, is too load the Windows mass storage device driver for the camera, instead of the camera driver.
If you haven't yet, check the manufacturers support site for instructions. I'm sure they've run into the problem before and have a better documented solution.