Are you getting severe entries in any particular queue? Can you provide more information. Usually the queue entry details shall provide you more information on the error.
actually I am new to Windchill and I have seen these kind of entries in Propagation queues more often.
I want a basic idea I mean what are these entries and why they occur .
There are multiple reasons why you would see a severe entry in propagation queue, for instance if an object on which a particular workflow process is initiated gets deleted , you will see a severe entry in the wfpropagation queue.
You can execute the QueueAnalyzer report to check the error in the entries, following article should help you:
Also, there are some additional trouble shooting techniques for workflow related issue, if that helps.