I'm not familiar with that software, but if it integrates with Outlook and
causes Outlook to malfunction, Outlook will disable the addin and give you
the Safe Mode notification.
See if the following key exists in your registry and if so, delete it;
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Resiliency
It will then will start in Normal mode again when you restart Outlook/your
PC.
Otherwise, uninstall the MagicJack software and see if it works again now.