Welcome to the forums, W4RP1G.
It sounds like you've got a launcher to launcher conflict going on.
The first thing I would do is get into the recovery menu and wipe cache, then reboot and see if it's allowing entry into the regular menu, where you can go into application manager and remove defaults on your old launcher.
Once that is done, you'll be presented with a launcher choice prompt, probably as you try to return to your home screen, but sometimes not until you reboot the device.
To get into recovery:
1. Turn your phone off.
2. Hold down “Home” and press “Power” until the Motorola logo appears.
3. Release ”Power” and continue to hold “Home” until an exclamation appears.
4. Release “Home” and press the “Search” button once.
5. Your phone will now enter recovery.