Unfortunately I cannot; the users have little or no familiarity with their machine operations. Users, not makers. However, I have now found out that the OSX version may have something to do with it. I cannot yet be certain. From one fellow I am working with on the issue:
“Panda3D is compatible with Mac OSX 10.4 (Tiger) through 10.6 (Snow Leopard) and the current OS is 10.9 (Mavericks) with 10.10 (Yosemite) soon to be released.”
Whether this is significant or not, I cannot say.
As for the .p3d file, I understand that it is the same except for the installer. It was something to try that might have yielded some information.
Cheers!