I recently ran into the problem that a normal working Universal connector stopped working and generated three different entries in the Application event log and alerts in the OpsMgr console:

EventID 1500:
2012-06-26 15:21:21.835 [Microsoft.SystemCenter.Interop.Framework.Modules.WSManModule] ERROR No
providers could be contacted.  Could not get update events.  Could not connect to any providers to retrieve update events

EventID 1501:
2012-06-26 15:20:53.944
[Microsoft.SystemCenter.Interop.Framework.Modules.WSManModule] ERROR Could not
deliver some events.  No providers were available.  Could not forward any provider

EventID 1516:
2012-06-26 15:20:53.944 [Microsoft.SystemCenter.Interop.Framework.Modules.WSManWrapper]
ERROR COMException An internal error occurred. 
occurred while sending event <p:CreateEvt_INPUT
xmlns:p="http://schemas.microsoft.com/wbem/wsman/1/wmi/root/scx/SCX_Connector"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

......

On the Management server where the Universal connector is installed, I opened a command prompt and browsed to c:\Program Files\System Center Operations Manager 2007 R2 Connectors\OpsMgr Universal Connector and ran the Interop Certificate tool to verify the connection

scicert.exe <hostname name of interop provider> <Domain\Username of the user also used in the connector config> <password> "OpsMgr Universal Connector" Test

This command opens a connection to the Interop Connector and verifies it, including the certificate. The result of the test showed that the SSL certificate was expired.

The SSL Certificate is generated when installing the Interop Provider and is valid for 2 years.

Following the guide here: http://technet.microsoft.com/en-us/library/dd795252.aspx solved the problem and the steps are:

1. Uninstall the Interop Provider

2. Delete the certificate

3. Install the Interop Provider again

4, Verify the certificate is valid for the next two years

5. Run the scicert.exe command on the connector server to import the certificate

6. Restart the connector service and you're back on track.

Note: The guide states the certificates are valid for 3 years, which is not correct, it is only valid for 2.