i have, though possibly not related to your problem.
i have a webserver which i run and have installed a perl module to stream mp3s. so all my mp3s are on my computer upstairs in my room. instead of moving everything, i set up an NFS export from my desktop computer. now, lazy person that i am i just dont feel like giving my desktop a static IP. when the lease on the ip from my router expires and i get a new, the NFS mount on the server goes stale.
when i try to do a directory listing inside the parent directory of the NFS mount, the shell locks up.
so have you checked to see if the NFS service is still running on the server-end ?
ps- my fix for the dynamic ip problem:
generally the ip address on my desktop only changes from 192.168.1.102 to 192.168.1.103 and back.
so, i have an NFS mount from BOTH ip address to the same place on the NFS client. i didnt know that would work and i actually dont know WHY that works...but it does