|The yellow exclamation mark in device manager means that you have NOT installed the driver that is required. You may think you have but that is not the one it wants.|
Also have you used other USB devices on your windows 98 before?
Your motherboard may require a generic USB driver to be installed. This should be on your motherboards driver CD.
Also be aware of this:
Some more links to help you:
☺ When everything else fails, read the instructions.