This problem can occur if the IPSec\Policy\Local registry key is deleted or when there is a corrupted file in the policy store. The file may become corrupted if an interruption occurs when the policy is being written to the disk
1. The following error is posted in the System Event log.
The IPSec driver has entered Block mode. IPSec will discard all inbound and outbound TCP/IP network traffic that is not permitted by boot-time IPSec Policy exemptions. User Action: To restore full unsecured TCP/IP connectivity, disable the IPSec services, and then restart the computer.
2. To correct start regedit. Please backup the key before making changes.
3. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\IPSec\Policy\Local
4. On the Edit menu, click Delete and click Yes
5. Quit Registry Editor
6. Rebuild a new local policy store, by clicking on Start, click Run, type regsvr32 polstore.dll in the Open box, and then click OK.
7. Verify that the IPSEC Services component is set to automatic, and then restart the domain