database errors

Our customer has problems with Pg 7.3.2 on Solaris.
There are numerous errors in the app. server log and in the database log,
including these:

LOG: open of /mnt_c1t2d0s0/<some-path>/postgresql/pg_xlog/0000000000000001
(log file 0, segment 1) failed: No such file or directory
LOG: invalid primary checkpoint record
LOG: open of /mnt_c1t2d0s0/<some-path>/postgresql/pg_xlog/0000000000000001
(log file 0, segment 1) failed: No such file or directory
LOG: invalid secondary checkpoint record
PANIC: unable to locate a valid checkpoint record
LOG: startup process (pid 16527) was terminated by signal 6
LOG: aborting startup due to startup process failure
...
ERROR: Cannot insert a duplicate key into unique index cr_pk
PANIC: RecordTransactionAbort: xact 55143 already committed
LOG: server process (pid 22185) was terminated by signal 6
LOG: terminating any other active server processes
WARNING: Message from PostgreSQL backend:
The Postmaster has informed me that some other backend
died abnormally and possibly corrupted shared memory.
I have rolled back the current transaction and am
going to terminate your database system connection and exit.
Please reconnect to the database system and repeat your query.

LOG: all server processes terminated; reinitializing shared memory and
semaphores
LOG: database system was interrupted at 2004-05-10 10:51:01 CDT
LOG: checkpoint record is at 0/30005E0
LOG: redo record is at 0/30005E0; undo record is at 0/0; shutdown TRUE
LOG: next transaction id: 53340; next oid: 57982
LOG: database system was not properly shut down; automatic recovery in
progress
LOG: redo starts at 0/3000620
LOG: ReadRecord: record with zero length at 0/3000930
LOG: redo done at 0/3000908
WARNING: XLogFlush: request 0/A970F68 is not satisfied --- flushed only to
0/3000930
WARNING: XLogFlush: request 0/A970FA8 is not satisfied --- flushed only to
0/3000930
WARNING: XLogFlush: request 0/A970E00 is not satisfied --- flushed only to
0/3000930
WARNING: XLogFlush: request 0/A970E40 is not satisfied --- flushed only to
0/3000930
FATAL: The database system is starting up
...
----------------------------------------------
We've had "Cannot insert a duplicate key into unique index" in the past.
We ran pg_resetxlog and reloaded the database - this helped.

I wonder if message
"open of /mnt_c1t2d0s0/... (log file 0, segment 1) failed: No such file or
directory"
may indicate some kind of NFS problem.

Anything else I need to look at?

Thanks in advance,
Mike.