This error is generated by Websydian and is normally seen on the iSeries platform running IBM HTTP Server.

The problem is that an eventhandler makes a call to more than one page generators. Calling more than one page generator from the same event handler will cause the dataqueues used by the Websydian application to be corrupted.

In order to isolate which event handler is causing this problem you will need to  make a note on the event handlers called and when the error occurs the event handler in error is the previous executed event handler.