Windows Explorer hangs

I am running Windows 2000 Service pack 2 on PC Workstations. I have 5 Novell,1 NFS, and 1 Windows 2k mapped drives. I log onto the network using Novells’ client. When I open Windows explorer and select a drive, mapped or not it may take up to 20 seconds to open the folder. Also when I do a file open from any application and use the drop down list I see the same problem.