If your computer prevents you from upgrading or uninstalling Fusion, you might have to use the Mac Activity Monitor to correct the problem.
In rare circumstances, the operating system in a virtual machine can quit unexpectedly in a way that leaves some virtual machine processes running. This situation can prevent you from upgrading or uninstalling Fusion. In this case, the installation or uninstallation Assistant might display a message that indicates that you cannot install or uninstall Fusion. To work around this problem, you can use the Mac Activity Monitor to force virtual machine processes to quit.