AVG Antivirus paid version installation issue

Hi! I had a free version of AVG antivirus installed. I just purchased a paid version for one computer. The free version was not allowing me to enter the license key so I uninstalled both the AVG antivirus and Zen. When I try to reinstall by downloading the installer from AVG site, I keep getting the error 'you already have another avg product on your computer that is incompatible…'.

I dont see any other AVG product installed. How does one resolve this problem? I had malwarebytes premium installed - I uninstalled this as well and then retried AVG install. But same error.

Any help?
Rgds
Suresh