classnotfoundexception

Hi, Im an organic chemistry student and I am trying to do practice prblems for my organic class and the mastering chemistry site is telling me that there is a "classnotfoundexception" with the marvin sketch applet. I have called pearson education, as well as disabled my antivirus and deleted my java cache. I really would like some assistance so that I can do well on my rapidly approaching chem exam. 
Thanks,
Spencer

Hi,

can you tell me which version of Java is installed on your system, which operating system do you use, with which browser and browser version do you try to access the site?

We had a report before, where the disabling of the antivirus system solved the problem, but because this was an acceptable solution, so we do not investigate the causes further that time, because it seemed to be an environment issue, so I need more information to be able to reproduce the issue. Can you tell me the exact url where you have the problems with Marvin applets, and I can check the used version and parameters with Pearson also?

Regards,
Istvan