I am having exactly the same issue. Unfortunately I didn’t check here soon enough to see the problem seems to be isolated to the preference pane which winds up in the “incompatible software” folder. Before uninstalling, the application seemed to be functioning fine other than the pref pane, and it launched just fine from the incompatible software folder.
After reinstalling the application (latest build) I also get hung up at the registration step. It does communicate with my existing avast! account and makes an entry for the installation, but it is incomplete. (Doesn’t recognize OS, etc.) As far as the installation goes, it appears to install normally, but does not register.
Hope there is a quick fix for this issue!