When 4.0 came out I downloaded and installed it. It would not open. I restarted my computer and tried to open 4.0. It would not open. I then tried to remove 4.0, but the uninstall wizard indicated that 4.0 was running. I restarted my computer, uninstalled 4.0 and reinstalled 3.6.

I went through the same process with 6.0 with the same results.