BrokerDoc Dispatcher Error

Hi,

We are constantly getting the following exceptions in our server logs:

[ISS.0098.0062D] DefaultInboundBrokerDocDispatcher encountered Exception: java.lang.NullPointerException

The subscriber stops subscribing from broker.CPU of the windows machine goes high after this.Restarting the IS again helps in correcting the issue.

Please let me know if anyone has faced this issue before and suggestions.

Thanks
Pravs