Just like Bert, I have used uninstaller programs for many years to fully clean computers of the junk left behind by the regular uninstall.
I have used both Your Uninstaller and a program which is very similar called Revo which is free. The AC uninstall leaves behind all the data and lots of stuff in the registry. I used the uninstaller program many times when initially working with AC to be able to do clean re-installs.
These programs generally work very well and are safe, but on one occasion, when taking the option to get rid of absolutely everything, a needed file was deleted, and then I had your same "run as administrator" problem. I eventually found the needed file in the Recycle bin and was able to restore it and get back in business.
Did you "reset the path" on the formerly main computer to use it as a client and direct it to look the the new main computer database? You will find this in the administrator options of AC.
