I assume both of you installed from the instructions here:
http://appinventor.mit.edu/explore/ai2/mac.html ?
Did you get through the firs eight steps?
Did you get through step 3 of these additional instructions?
Do either of you use AVG, Eset or AVAST virus checkers? There have been issues with them on Windows systems where going into their Advanced Link settings and allowing AI2 fixed their issues. I am not sure your Mac issues are similar but worth mentioning.
Have either of you tried WIFI or USB? If so, with what results?
I am suggesting that both of you try to re-install. It appears something happened with your original installation. You may have missed a step, a program running in the background may have interfered with the install etc.
On the Mac
Perform these steps in order:
- Logout, or reboot your computer. (Important!)
- Download the new Mac installer package
- Install the new software you just downloaded. Do not change the installation directory from the default that the installer picks.
I'm about out of suggestions. Try reinstalling, a different browser of check if your virus checker is one of the ones some users have issues with. Also, do either of you have ad blockers ...these too interfere with AI2.
Regards,
Steve