CASA Uninstall issue

I had a end user that shutdown his computer before the uninstall of ZCM10.3 agent was finished and now I can't seem to get CASA uninstalled correctly. I tried the Agent Cleanup utility but it also errors. Is there a way to tell Windows 7 that CASA is no longer installed so I can successfully install ZCM11? When trying to install ZCM11 agent it failes on bundle 2 (Casa install). I am assuming it is a registry entry in Windows7 that might be preventing this but I haven't been able to find it.

Thanks

Rich