I recently downloaded and installed Ubuntu 12.04 LTS on my Mac (OS X 10.7) running Parallels Desktop 7. My mouse worked just fine. Then I installed Parallels Tools for Ubuntu and rebooted. My mouse cursor never appears and mouse clicking is not recognized. The keyboard works properly. I can Ctrl-Alt to release the mouse back to OS X. I went into Ubuntu's Mouse System Settings and activated the "Show position of pointer when the Control key is pressed". This function works okay and "shows" where my mouse pointer is (but, of course, does not show the pointer icon itself). But if I move my mouse, the position of the "invisible" pointer does not move. If I uninstall Parallels Tools for Ubuntu, after rebooting, my mouse works properly within Ubuntu. If I once again reinstall Parallels Tools, after rebooting, my mouse is non-functional again. Ideas?