multiple failed logons, local guest account lockouts logged, then backup succeeds

Hello,

We have Acronis Backup and Recovery 10.0 and have backups running daily on 15-20 systems.
We have noticed multiple failed logons logged in the security logs on a subset of the systems at the time of backup. There are usually 3-5 failed logon attempts via NTLM (no username listed), then a successful logon of the domain account that the backup services run under via Kerberos. We also see a message stating that the local guest account has been locked out on the systems that have the failed NTLM logons.
The same subset of systems has these failed logons at the same time every day. The failed logons and guest account lockouts disappeared when backups were turned off for 2 weeks.
I'm sure that a password for an Acronis account was inadvertently changed somewhere along the line but I'm not sure where to look for Acronis-specific logs that may shed some more light on this. The backups are still completing successfully and we have confirmed that they have data, so it looks like once the first account fails to connect (whatever that account is), then it automatically tries the domain account.

Has anyone else seen this? Any suggestions on how to track down what this account is and how to fix it outside of a complete re-install are greatly appreciated.

Thank you