Also, your hitting this 3 activation limit because your install is not activating on your kms server which prevents this issue. Windows is complaining because your circumventing the grace period by syspreping repeatedly. Add this section to you oobeSystem pass section to force windows to activate on your KMS server during sysprep. Note the key is for win 7 enterprise, if your using another version get the keys here:

Access Windows 7 KMS Client Setup Keys - Softpedia

Code:
 
                
                    1
                    false
                    cscript //b c:\windows\system32\slmgr.vbs /ipk 33PXH-7Y6KF-2VJC9-XBBR8-HVTHH
                
                
                    2
                    cscript //b c:\windows\system32\slmgr.vbs /ato
                    false