Java 7 is not completely backward compatible with previous versions of Java and this version has broken a number of Physlets.   There is, however, a new Physlet.jar that corrects for these Java 7 bugs.  

http://www.compadre.org/osp/items/detail.cfm?ID=10710

Download the jar and replace all reference to multiple jar files in an HTML page with a reference to this single jar.  

I have found and fixed problems with Optics Bench, B Field, and the 3D E&M Wave Physlet.  Although we are unable to correct problems with the Prentice Hall (Pearson) CDs,  material from these CDs will soon be available on ComPADRE.

Post edited March 9, 2013 at 10:51 AM EST.