Hi, this sounds like a strange issue. Please let me know if you can perform these steps and what happens when trying them.
1. Re-start your Mac and make sure you have an active Internet connection.
2. Plug your magicJack into your Mac.
Note: On Mac Mini or other macs, do NOT use the USB port on the keyboard.
Your magicJack needs to be plugged into the port on your computer or into a powered USB hub.
3. Mac OS will recognize your magicJack device and mount its drives. Two drive icons will appear on your desktop.
4. Depending on the OS version and settings, a window may open with the instructions to run magicJack by clicking the magicJack icon. If it does not open, please double-click the mounted “magicJack” drive.
5. In the displayed window, double-click the large magicJack icon.
The program should open up and function normally. Your account may be disabled, have you contact Magic Jack?