Windows Explorer opens slowly

Windows Explorer always takes a long time to open on one of our computers, sometimes up to 90 seconds, and it’s the only program I’m trying to run. It’s running 98SE on a Dell Dimension L600cx, has 128MB RAM, the HD is 1/10th full. All other programs open fast. The HD is defragged once a week. I’ve never seen it open this slow on another computer. Any suggestions?