I see many threads on this. PT does not start or there is no icon in the system tray. I have installed PT on 3 systems: 2 Win 7 32 bit and 1 Win 7 64 bit. It starts fine on 1 32 bit system and the 64 bit, but not the other 32 bit system. It doesn't show up as a running process. The only thing different is that this system has a quad processor and the others are duo processors. I have tried both putting this into the registry and the startup menu, but nothing works. There is obvioulsy something environmental, but I have no idea what it is. All the systems are up to date as far as Windows maintenance.