where can I find reason for this exception message from tomcat?

, mssqlserver.jar, msutil.jar and located on %JAVA_HOME%\jre\lib\ext. The web application is working just as interface for user authentication. It works well about 2-3 weeks after starting tomcat and then suddenly fail to authenticate user. User data still on the proper table. I found exception message from

Exception message

hi, I'm new user of tomcat web server. I'm able to setup the web server and view the default Tomcat home page but sometimes I got an exception message displayed on my dos screen when I try to run the my test program. Is my program caused this exception or the setup ? Thanks Here

RE: Exception message

I'm new user of tomcat web server. I'm able to setup the web server and view the default Tomcat home page but sometimes I got an exception message displayed on my dos screen when I try to run the my test program. Is my program caused this exception or the setup ? Thanks Here