fsync and semctl errors with 8.1.5/win32

I've been attempting to run PostgreSQL 8.1.5/win32 on a production
deployment, but have started having many problems. McAfee Antivirus is
installed and running, although I've excluded the entire drive where
PostgreSQL is installed and where the data is installed.

I've received several errors in the past few days/weeks. They fall into
three general categories 1) permission denied errors 2) semctl errors 3)
fsync errors. I am not sure how to reproduce these errors locally -
they seem to occur at unpredictable intervals.

The following posts seem related, although I don't see a resolution for
any of the problems listed:
http://www.mail-archive.com/pgsql-bugs(at)postgresql(dot)org/msg16097.html
http://www.mail-archive.com/pgsql-bugs(at)postgresql(dot)org/msg14792.html
http://www.mail-archive.com/pgsql-bugs(at)postgresql(dot)org/msg14916.html

I have run PostgreSQL on Linux in the past and not had any problems. Is
the win32 build generally considered stable or unstable for production
use? Any help would be greatly appreciated!

1) PERMISSION DENIED ERROR
This error occurred on the same day as the semctl started, but stopped
occurring for a few hours before the semctl errors started.

The following is an example:
2006-11-25 00:46:04 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:05 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:06 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:07 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:08 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:09 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:10 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:11 ERROR: could not open relation 1663/16404/84855:
Permission denied
2006-11-25 00:46:12 ERROR: could not open relation 1663/16404/84855:
Permission denied

2) SEMCTL ERROR
This error occurred over and over one day with the same pattern -
several semctl errors, then the unexpected EOF. This resulted in
clients being unable to create database connections. The error occurred
overnight and into the next day, and did not disappear until postgres
was restarted.

The following is an example:
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 FATAL: semctl(167238064, 15, SETVAL, 0) failed: A
non-blocking socket operation could not be completed immediately.
2006-11-25 22:10:03 LOG: could not receive data from client: No
connection could be made because the target machine actively refused it.
2006-11-25 22:10:03 LOG: unexpected EOF on client connection

3) FSYNC ERROR
I've seen this error several times in the past - including today.

The following is an example:
2006-11-27 00:00:20 LOG: autovacuum: processing database
"incommDashboard"
2006-11-27 00:00:20 LOG: could not fsync segment 0 of relation
1663/16404/89952: Permission denied
2006-11-27 00:00:20 ERROR: storage sync failed on magnetic disk:
Permission denied
2006-11-27 00:00:24 LOG: could not fsync segment 0 of relation
1663/16404/89952: Permission denied
2006-11-27 00:00:24 ERROR: storage sync failed on magnetic disk:
Permission denied
2006-11-27 00:00:26 LOG: could not fsync segment 0 of relation
1663/16404/89952: Permission denied
2006-11-27 00:00:26 ERROR: storage sync failed on magnetic disk:
Permission denied
2006-11-27 00:00:29 LOG: could not fsync segment 0 of relation
1663/16404/89952: Permission denied
2006-11-27 00:00:29 ERROR: storage sync failed on magnetic disk:
Permission denied
2006-11-27 00:00:32 LOG: could not fsync segment 0 of relation
1663/16404/89952: Permission denied
2006-11-27 00:00:32 ERROR: storage sync failed on magnetic disk:
Permission denied
2006-11-27 00:00:42 LOG: could not fsync segment 0 of relation
1663/16404/89952: Permission denied
2006-11-27 00:00:42 ERROR: storage sync failed on magnetic disk:
Permission denied