It is not normally necessary to install the Pro version if there is a Home version already running. My understanding is that entering the license key you have purchased will be adequate to activate the Pro features.
If you continue to have problems, I would suggest a full re-install from scratch.
If you would like detailed directions on doing this, including the use of the Uninstall utility, please post back.
Dial a Fix is a good application. Contains many "fixes" for various system problems. Care should be taken in its use, however. If you aren't fairly sure about what a fix is supposed to do, best ask first. But it can't do any irreparable damage.