Event ID 565 Failure Audit. WHAT DOES IT MEAN?

Exchange 2003, Cluster of 2 servers running 2003 Server.  I am getting some Failure Audits in the Event Log that dont make much sense.  The event ID is 565.  Lets say I have Jim, Mark, and Zach.  I will see these failure audits from Jim on Jim's account.  Same for Mark and Zach.  What I found is that I have seen these same audits only they were on Mark and Zach's account but they were caused by Jim.  I could recreate the audit if I tried to open another persons mailbox so I thought that Jim might be trying to read other people's mail.  He tells me that they were probably caused by Meeting Requests that he sent out and surprisingly they match up.  But then I found some more of these audits only they dont match up with any Meeting Requests.  Here is an example of an audit I have seen.


6/28/2006 8:26:23 AM Failure Audit Security SERVER01
  Object Open:
Object Server: Microsoft Exchange
Object Type: Microsoft Exchange Logon
Object Name: /o=Exchange2003/ou=First Administrative Group/cn=Recipients/cn=ZACH
Handle ID: -
Operation ID: {1,1835013326}
Process ID: 5240
Process Name: C:\Program Files\Exchsrvr\bin\store.exe
Primary User Name: APCLUS01$
Primary Domain: OPNT
Primary Logon ID: (0x0,0x3E7)
Client User Name: JIM
Client Domain: Domain
Client Logon ID: (0x1,0x6CEB0ED9)
Accesses: Unknown specific access (bit 8)

Privileges: -

Properties:
---
%{ab721a54-1e2f-11d0-9819-00aa0040529b}
%{bf967aba-0de6-11d0-a285-00aa003049e2}

Access Mask: 0

To me it looks like Jim is trying to access Zach's account but there is no definitive statement to this effect.  Any help would be great.