Resolution:
If a Command service destroy method or EngineHook terminated method is used, a Hotspot error may occur on Solaris Engines, writing a hotspot error log in the Engine's directory. The Command destroy method may also result in locked invoke processes remaining on the Engine.

The log will be of the form:

Unexpected Signal : 11 occurred at PC=0xEEE7C07C
Function=JVM_NativePath+0x350
Library=jre/lib/sparc/server/libjvm.so

Current Java thread:\\at java.lang.Object.notify(Native Method) at com.livecluster.util.ReusableThreadPool$InternalThread.run ....

This can only be avoided by not using these methods.