Event 4740 not being logged on a domain server

Deleting the user accounts and recreating them seemed to do the trick. Tried logging on to the machine as the service account didn't work, so i figured there had to be something wrong with the account. deleted it, added it, now it's all working again..

Members of local built-in groups (as well as domain groups) have whatever rights are assigned to the group. The default rights on a server for local built-in groups are set in the local security settings. To access the local security settings, click Start, type secpol.msc and hit enter. In the Local Security Policy editor, expand Local Policies, and click on User Rights Assignment. There you will see what groups/users are granted which rights.

The local User Rights Assignment settings can be overriden by domain group policy. If you create a domain group policy that grants certain groups/users a certain right, such as "Logon as a batch job", this will override the local policy for which users have that right.

From what you have written, here is what I am guessing happened: You had a GPO in your domain that granted certain users the rights that you mentioned. This policy did not grant these rights to local machine Backup Operators group. This policy overwrote the default policy on the server. Thus, adding the user to the Backup Operators group did not give them those rights because, due to the Domain GPO, the Backup Operators do not have them.

As to whether or not the vendor's solution is a good idea: I have found that it is usually easier to manage rights by using well-organized groups rather than granting them to individual accounts. This way, when you add a new user, you add the user to the logical groups to which he belongs, and he will immediately have all of the rights he needs rather than having to assign him each right one-by-one. That is what the Built-in groups were intended to do.

Instead of granting those three rights to an individual user, you could have granted the "Backup Operators" group those three rights in the GPO. Then adding the user to that group would have the intended effect.

I am curious why you would have a domain policy managing those rights in the first place. If the purpose was to grant certain users access to perform backup operations, it might have been a better idea to use the domain built-in Backup Operators group.