ID 7: Unable to connect to the Active Directory Domain Services

During the deployment or the attaching of agents you might run in to the error below.

Unable to connect to the Active Directory Domain Services database. Make sure that the DPM server is a member of a domain and that a domain controller is running. Also verify that there is network connectivity between the DPM server and the domain controller. ID: 7 Details: Unknown error (0x80005000) (0x80005000)

There is a knowledge database article for a issue like this:
http://support.microsoft.com/kb/978900

Resolution for Error ID: 7 To resolve this error, change the Authenticated Users group so that it has read permissions for the organizational unit that the target server is a member of. To do this, follow these steps: On the domain controller, open the Active Directory Users and Computers MMC. Right-click the organizational unit that contains the target server, and then click Properties. On the Security tab, add the Authenticated Users group and give them READ permissions. Redeploy the DPM protection agent to the protected server

Alternative cause to this issue

The error code Unknown error (0x80005000) (0x80005000) points to another cause.

In this case the issue was caused by a slash in the OU Name the  The target machine to install the DPM agent on was in an OU named "DR/ test Servers."  DPM doesn't understand special characters in active directory, so the / was what tripped it up.  When you rename the OU, you should be y able to install the agent.