Possible Unathorized Access on Windows 2000

I recently had to wipe my Windows 2000 Server clean and start over due to hacker activity.  Thius time I beefed up security considerably but I am wondering if some activity I am seeing could be more unauthorized access.
Every day at 4:40pm the event log shows a change password failure attempt.  It is only 1 to 3 attempts and then the activity stops.   Yesterday I had the attempt and it appeared possibly it was successful.  I'm not sure since the logs are usually so cryptic.
At 4:40:13 it said:
Event Type:    Failure Audit
Event Source:    Security
Event Category:    Account Management
Event ID:    627
Date:        3/28/2007
Time:        4:40:13 PM
User:        NT AUTHORITY\SYSTEM
Computer:    EAP3
Description:
Change Password Attempt:
     Target Account Name:    TsInternetUser
     Target Domain:    EAP3
     Target Account ID:    EAP3\TsInternetUser
     Caller User Name:    EAP3$
     Caller Domain:    WORKGROUP
     Caller Logon ID:    (0x0,0x3E7)
     Privileges:    -
 

Then the next entry said:
Event Type:    Success Audit
Event Source:    Security
Event Category:    Object Access
Event ID:    560
Date:        3/28/2007
Time:        4:40:13 PM
User:        NT AUTHORITY\SYSTEM
Computer:    EAP3
Description:
Object Open:
     Object Server:    Security Account Manager
     Object Type:    SAM_USER
     Object Name:    DOMAINS\Account\Users\000003E8
     New Handle ID:    928064
     Operation ID:    {0,44024875}
     Process ID:    264
     Primary User Name:    EAP3$
     Primary Domain:    WORKGROUP
     Primary Logon ID:    (0x0,0x3E7)
     Client User Name:    EAP3$
     Client Domain:    WORKGROUP
     Client Logon ID:    (0x0,0x3E7)
     Accesses        ChangePassword (with knowledge of old password)
           
     Privileges        -
 

The above says to me that maybe there was a successful password change.  Even so, there are no login events for a week that were not from me.

Then after that there were two more failed attempts at 4:40:16.
Event Type:    Failure Audit
Event Source:    Security
Event Category:    Object Access
Event ID:    560
Date:        3/28/2007
Time:        4:40:16 PM
User:        NT AUTHORITY\SYSTEM
Computer:    EAP3
Description:
Object Open:
     Object Server:    Security Account Manager
     Object Type:    SAM_USER
     Object Name:    DOMAINS\Account\Users\000003E8
     New Handle ID:    -
     Operation ID:    {0,44025011}
     Process ID:    264
     Primary User Name:    EAP3$
     Primary Domain:    WORKGROUP
     Primary Logon ID:    (0x0,0x3E7)
     Client User Name:    EAP3$
     Client Domain:    WORKGROUP
     Client Logon ID:    (0x0,0x3E7)
     Accesses        ChangePassword (with knowledge of old password)
           
     Privileges        -
 

I don't even know how they are getting an interface to make the attempt since a proprietary SmTP (port 25), IIS (port 80), and Terminal Services (on port 8238) are the only things open.

Thanks.
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r-kCommented:
I think this is normal. See this previous thread:

 http://www.experts-exchange.com/Microsoft/Windows_Security/nullQ_21459239.html
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