New version of Backupper refuses to install

I had a previous version of Backupper on my Windows 7 machine. I uninstalled it before trying to install the new version. As part of the uninstallation I restarted the computer as instructed. Next I tried to install the new version, but after the first screen or two of the setup it displays a message saying "Setup has detected a restart required to perform the uninstall. Please restart and try again." I restarted again...and again....and again. Every time I try to install the new version it gives me that same message and won't let me continue the installation. I have also tried re-installing the old (2012) version to see if that would work, but it gives me the same message.

What can I do?

Thanks in advance for any suggestion.