Hi, just wanted to pop in and post on this thread in case people are still having problems.
I have Windows 7 x64 and went through all of the fixes in this thread, could not get it to work. It would still hang on launch and I would have to end task. I tried the fix they issued and would get the "did not install, not present" error. So right before I uninstalled it, I then went in and right clicked the icon, and clicked on "Compatability Mode" and selected Vista SP2. Then it fired right up. I also have to say, I am VERY impressed with this software.
On a side note, the problem with registry keys is very common. There are tons of programs that leave registry keys. A good program to use to clear those out is CCleaner, its freeware and attaches to your recycle bin. Just open it up, select registry and it will do a scan to find all the old keys, then you can delete them.
Good Luck!