Mapped Drives Failed

All of a sudden, all mapped drives on our windoze 98 machines say that the network path cannot be found to our 2K server. I can ping the server successfully from the workstations, but cannot access any of the shared files. This doesn't seem to be a problem that snuck up, it happened all of a sudden, and a simple re-start didn't do the trick - Any insights would be very helpful at this point!