Recently we had the following error occur on our Dynamics CRM installation:
Current key (KeyType : CrmWRPCTokenKey) is expired. This can indicate that a key is not being regenerated correctly. Current Key : CrmKey(Id:XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX, ScaleGroupId:00000000-0000-0000-0000-000000000000, KeyType:CrmWRPCTokenKey, Expired:True, ValidOn:02/06/2015 17:39:15, ExpiresOn:03/11/2015 17:39:15, CreatedOn:02/06/2015 17:39:15, CreatedBy:NT AUTHORITY\NETWORK SERVICE.
Turns out this was due to a service not coming up correctly after a power failure. Make sure Microsoft Dynamics CRM Async (maintenance) service is up and running. Restart the non maintenance one or make sure this one is started too.
Now with both of these running the problem was fixed.