Network Login Attempts

I'm having a strange issue whereby a PC keeps on trying to connect to our file server as an account that's not recognised by the server. Looking at the event on the server it's trying to connect to, the login attempt is coming from a local account that we've setup for local administrative purposes. But I don't know why that account would be trying to connect to the file server. We do map drives from this server but the local account shouldn't be trying to map any drives. Here's the event from the server.

 An account failed to log on.

Subject:
    Security ID:        NULL SID
    Account Name:       -
    Account Domain:     -
    Logon ID:       0x0

Logon Type:         3

Account For Which Logon Failed:
    Security ID:        NULL SID
    Account Name:       itadmin
    Account Domain:     D00594

Failure Information:
    Failure Reason:     Unknown user name or bad password.
    Status:         0xC000006D
    Sub Status:     0xC0000064

Process Information:
    Caller Process ID:  0x0
    Caller Process Name:    -

Network Information:
    Workstation Name:   COMPUTERA
    Source Network Address: 192.168.x.x
    Source Port:        64468

Detailed Authentication Information:
    Logon Process:      NtLmSsp 
    Authentication Package: NTLM
    Transited Services: -
    Package Name (NTLM only):   -
    Key Length:     0

This event is generated when a logon request fails. It is generated on the computer where access was attempted.

The Subject fields indicate the account on the local system which requested the logon. This is most commonly a service such as the Server service, or a local process such as Winlogon.exe or Services.exe.

The Logon Type field indicates the kind of logon that was requested. The most common types are 2 (interactive) and 3 (network).

The Process Information fields indicate which account and process on the system requested the logon.

The Network Information fields indicate where a remote logon request originated. Workstation name is not always available and may be left blank in some cases.

The authentication information fields provide detailed information about this specific logon request.
    - Transited services indicate which intermediate services have participated in this logon request.
    - Package name indicates which sub-protocol was used among the NTLM protocols.
    - Key length indicates the length of the generated session key. This will be 0 if no session key was requested.

We do also have a domain account under the same name as the local account, but because of the lack of DOMAIN\username in the event log it leads me to believe the attempt is coming from a local account but I may not be correct on this.

I've checked for any scheduled tasks running under this account and cannot confirm any. I've also confirmed that the local account doesn't have a user profile on the affected system. I've also checked the Security Event logs on the local machine and can't identify any coming from the affected account.

Can anyone help me with this, are there other events I can look for on the affected system or server that can help me identify this account. We're getting over 100+ events a day on the server and it's becoming a real pain to troubleshoot.

Thanks in advance.