Mac OS X 10.1.5 introduced a generic PC card modem driver for a variety of PC card modems. However, if after using the modem one switches to a network location for which the PC card modem port is not active, a kernel panic can occur and the computer will need to be restarted.
Symptom
A kernel panic occurs when you switch network locations or when you eject a PC card (PCMCIA) modem. If you need help identifying this symptom, see technical document 106227, "Mac OS X: What is a Kernel Panic?".
Solution
This resolved in Mac OS X 10.2 or later. Users of Mac OS X 10.1.5 may use the following workaround.
For each network location you use, enable the port for the PC card modem. Follow these steps:
Alternatively, you may eject the PC Card modem while the computer is in sleep mode.