EventID 540 Anonymous Logon

This morning when I logged on my machine I noticed this event log:

Event Type:    Success Audit
Event Source:    Security
Event Category:    Logon/Logoff
Event ID:    540
Date:        8/10/2006
Time:        5:09:03 AM
User:        NT AUTHORITY\ANONYMOUS LOGON
Computer:    IKCICHOCKI2
Description:
Successful Network Logon:
     User Name:   
     Domain:       
     Logon ID:        (0x0,0x1125A)
     Logon Type:    3
     Logon Process:    NtLmSsp
     Authentication Package:    NTLM
     Workstation Name:   
     Logon GUID:    {00000000-0000-0000-0000-000000000000}


Cany anyone tell me what this could be about?
Being a successful Network Logon worries me.