NFS server problems?

[adp]

I occasionally see error messages on NFS clients such as:

nfs server files:/rmt/mnt: not responding
pmap_collect: collecting pv entries -- suggest increasing PMAP_SHPGPERPROC
got bad cookie vp 0xdc92a9c0 bp 0xcc578fac
got bad cookie vp 0xdc92a9c0 bp 0xcc578e60

NFS actually runs fine. We haven't had any real problems.

On the client I do see some errors:

# nfsstat -c
Client Info:
...
Rpc Info:
 TimedOut   Invalid X Replies   Retries  Requests
       26         0       162       508    405121

My thoughts are a bad cable or switch going to the NFS server, but I'm
curious what others think.

This happens on multiple NFS clients.

(Well, I only found the PMAP_SHPGPERPROC entry on one.)

The NFS server is FreeBSD 4.9-STABLE and the clients FreeBSD 4.10.