CVS server hangs after returning several files. No error messages.

[John Nagle]

OS: Red Hat Linux/x86
CVS versions:
Client: Concurrent Versions System (CVS) 1.11.2 (client/server)
Server: Concurrent Versions System (CVS) 1.11.2 (client/server)
CVS root: ":pserver:localhost:/cvs"
CVS is running in a chroot jail via pserver. 


 Our CVS server has failed.  It will deliver a few
files on checkout or update, then hang.  Typical
session:

$ cvs update
? .new.QNXSPA02.
cvs server: Updating .

(hangs indefinitely)

  The same thing happens for access over the net and for
local access via localhost.

  The machine it is running on is essentially idle,
with near-zero CPU load and no disk activity.  
The underlying files are on a RAID disk, and the disk
system indicates the files are undamaged.  This CVS
server has been running for months without problems.
There's plenty of disk space available.  There
are no error messages in /var/log/messages.  

 It just hangs.

 Any ideas?

                        John Nagle