I get the following error on the workstation import/remove screens

Error occurred during the intialization of VM
java.lang.NoSuchMethodError:
java.lang.Thread.holdsLock(Ljava/lang/object;)Z

(press any key to close screen)

I just upgraded from zen 6.5 to version 7 hoping it would fix the error. It started after I upgraded from version 4 to 6.5. I've copied the zenworks/inv/jre folder from a working zen 7 server and still same error.

Thanks
Aron