NPE

My java applcation is throwing a NullPointerException on some data. The applications is multithreaded application that takes data as input, processes it and sends it. On some of the data I get a NullPointerException , but no stack trace. After investigating them I did not see a difference between the data that causes NullPointerException and the data that doesn't. The only difference I get is that when the NullPointerException occurs the application has a high load.