Network drives not responding

Hi, Got a Windows Explorer error on one of the Desktops at work. The desktop is running Windows 2000. When going into Windows Explorer and trying to access network drives(f,s,t), the Windows Explorer stops responding, cannot see any network items. Going into C:/drive is ok. I have applied the latest Windows update, done the usual virus checking and defragging the hard drive.

Please help

Regards
Dave