A WMDocument Exception was thrown in the server usually because an XML block was not

Hi All,

In our production SFDC is invoking webMethods webservices. Intermittent we are getting following exception " A WMDocument Exception was thrown in the server usually because an XML block was not " I am unable to reproduce this issue in our dev box. we are running on 8.0 IS_8.0_SP1_Core_Fix17
IS_8-0_SP1. Please share your expert thoughts we need to apply any patch or fix for this error?

Thanks in Advance,
JSree

when we reprocess the same request using our Internal resubmitting mechanism it is working fine.