Issue
You configured a custom CQ Service placed in /classes/.../serviceclass. If you try to access this CQ Service from a JSP script (by ServiceManager.getService(), you get a ClassCastException.
Solution
To make sure that your class is loaded from the same classloader put your class file (including the package directory hierarchy) into a jar file. Then, copy it to /system/bin.new/lib. The com.day.cq.bootstrap.BootClassLoader loads your class. The service manager as well as the JSP system use the com.day.cq.bootstrap.BootClassLoader.
Make sure that your class isn't in /classes/... or still in the class cache (/system/works/classes) from an earlier compilation in cqde. Then, restart.
Additional information
The ClassCastException occurs when the service manager and the JSP system don't use the same classloader. Therefore, your class isn't the same for the service manager and the JSP system.