Exchange stops working

Hi we have been running exchange 2003 on sbs 2003 for about a year now,
nod32 enterprise has been running on this for about the same time.

in the last month or two we have been experiencing problems with our exchange server stopping(maybe freezing)

when checking the server event logs i can only see that something is installed each time the problem occours. (See below)

Event Type: Information
Event Source: MsiInstaller
Event Category: None
Event ID: 11728
Date: 12/19/2006
Time: 9:05:18 AM
User: \Administrator
Computer: SERVER
Description:
Product: ProductContext -- Configuration completed successfully.

For more information, see Help and Support Center at http://notpromotingmicrosoft.com.
Data:
0000: 7b 35 39 37 44 37 33 41 {597D73A
0008: 38 2d 35 46 44 42 2d 34 8-5FDB-4
0010: 42 43 31 2d 39 38 39 33 BC1-9893
0018: 2d 34 30 42 35 34 34 35 -40B5445
0020: 39 46 31 42 43 7d 9F1BC}


when checking the server today after it happening again i noticed that nod had updated.

in the nod event logs it appears that after it updates it can nolonger read from exchange. extract from log below

Time Module Event User
12/19/2006 11:36:25 AM XMON Failed reading 2048 bytes from stream. NT AUTHORITY\SYSTEM
12/19/2006 11:36:25 AM XMON Failed reading 2048 bytes from stream. NT AUTHORITY\SYSTEM
12/19/2006 11:19:40 AM Mirror Mirror has been updated successfully.
12/19/2006 11:19:34 AM Kernel The virus signature database has been successfully updated to version 1928 (20061219).

has anyone experienced this before, or have any idea why this might be happening.

if it was possible to get nod to run a bat file after updating it wouldnt be so bad as i could get exchange to restart.

i would be gratefull for any help on this