java.lang.UnsupportedClassVersionError: Bad version number in .class file (unable to load class org.

Hi,
I am facing issues in running reports on Ubuntu server:
Details of the software installed are:
Tomcat version is: 6.0.35
JRE version is: 1.5.0 update 17
JVM version: 1.5.0_17-b03
OS version: 2.6.18-164.0.0.0.1.el5xen

I have tried moving the driver to tomcat/lib folder but still the error is same.The error is attached for your reference.

Please can anyone help me with this.

Regards,
Shruti