Hi Simon,
I'm guessing it's trying to show Affixa's in-built web browser so you can log in and grant Affixa access to the email account. That's the only ActiveX component in the whole solution.
My default suggestion would be to uninstall and reinstall since it would most likely be a DLL registration issue, but you say you've suggested that.
Next best guess is that there's something on the PC restricting Affixa somehow. Some security or anti-malware software, maybe? Or maybe that prevented the installation of a DLL when the installer was running?
You should see a DLL named csExWB.dll in the "Affixa" folder on the C: drive.
All the best,
Chris