Question: Java Error on Client Systems

My school deployed the application for examination purposes, got this app installed on a server and deployed. but question is this

1. when a student logs in with his or her id and click on the assignment link from a client system connected to the server and start attempting the assignment, at a time the question will stop responding, responding in the sense that one will not be able to next or back the question. and if such student close the assignment page and logs out to re-login back. then java error will start appearing and that means the said student wont gain access any more to attempt the assignment.

2. Secondly, if a student succesfully completed his or her assignment when click on grade, what comes out of such action is java error.

PLEASE HELP AS WE ARE CURRENTLY IN OUR EXAMINATION PERIOD AND THIS ERROR HAD MADE THE INSTITUTION TO START RE-SCHEDULING A DATE FOR THE ASSIGNMENTS THE ERROR OCCURED ON, PLEASE HELP.

THANKS