We run our SQL server process under a domain account and changed the password in the run up to upgrading to VC Update 4. The account kept locking out during the install process. The issue ended up being with Update Manager. I uninstalled it and everything started working without the lockouts. Update Manager was not running under a domain account so I'm not 100% why it was causing the lockouts. I pinpointed this by stopping and starting that service and checking the to see if the account failed to logon to AD.

I also had this problem and tracked it down to a trial version of VKernel's Capacity Analyzer. If you're having the issue, I suggest you check 3rd party apps first.

SandyB, check 2 things:

1) Verify that no servives are running on the host, under the context of the domainadmin - if any are, this should be changed to use a different user account, to prevent this kind of thing happening (create a dedicated Service account)

2) Check that your DB does not use Domain admin for access.

Good luck - please post back with your resolution

Incidetally, Microsoft has a tool called EventCombMT that will allow you to query your DCs / event logs for event lockout events