SQL authentication error in Forefront Client Security

Hello,

I have a SQL authentication error in Forefront Client Security

Date3/17/2014 9:58:02 AM
LogSQL Server (Current - 3/17/2014 9:58:00 AM)
SourceLogon
Message
Login failed for user 'AD\user'. [CLIENT: 1xxx.xxxx.xxxx.xxx.xxx]

...

I suspect a missing SPN registration but not sure wna what should it be?

Thanks,
Dom

System Center Operations Manager 2007 / System Center Configuration Manager 2007 R2 / Forefront Client Security / Forefront Identity Manager