Droping connection to network drives

I am having a problem on one of my site. User has Dell Laptop with WIN98SE. OS keep dropping connection to network drives. When she login in the morning she can access network drive but after sometime she get access denied msg. Disconnection is sporadic. Sometime it happens after few hours sometimes whole day go by without a problem. Site has Windows 2000 server. We already run DSClient on laptop. Laptop has been refresh couple of weeks ago and user having problem since then. She is the only one having this problem. Any help would be appreciated.