updating jars in WEB-INF\lib folder are not recognize

I am new to this blog. Really i am having a problem. I replaced the old jars with my new jars in WEB-INF\lib folder. We are using Tomcat5 server. After moving my jars, i restarted the tomcat5 server. While testing the module, it is throwing exception. Because the updated jars are not taking effect.

Kindly help me ASAP. Thanks in advance.