Apple external modem causes apparent freezing

When the Apple's external USB modem is in use, users may experience what appears to be a system hang after a few minutes of being connected. For some users the computer must be reset multiple times before the modem will initialize properly and connect. This behavior affects all Macintosh models and appears to be random in occurrence, as one Apple Discussions poster, Matt R, writes:

"Sometimes it takes 5-6 restarts to get it to connect, then it hangs after 4 mins online. Then the next day it'll connect no problem and stay online for over an hour."

Despite the apparent freeze/crash it seems the computer may be functioning normally, with only the keyboard and trackpad not working. One MacBook Pro user mentions when playing music the crash will not pause the songs, but the computer stops responding to key presses:

Another user, Chris Byrd, wrote:

"If iTunes is running in the background, songs will continue to play, but you can't navigate to anything. The function keys don't work, and even the caps lock doesn't light up when you hit it."

On a similar note, as described in a thread on the Apple discussion boards, other users who have not experienced crashes have experienced dropped connections with the modem after a few minutes, indicating either the modem itself may be faulty or there may be a modem driver conflict in Leopard.

The "crashes" experienced appear to be from a conflict between the Apple modem and other devices sharing the same USB bus. When the modem causes this conflict, any other device connected to the same bus will stop working as well, including keyboards and mice. As such, the computer itself may not be crashed; and, depending on the Macintosh model, there may be another USB bus available for use. For instance, in Mac Pro systems the rear USB ports are on a different bus than those on the front of the unit. The same goes for MacBook Pros, where the ports on the left are on a different bus than the one on the right (which is also shared by the keyboard and trackpad).

Fixes

Since the problems with the USB modem seem to have appeared in Leopard, hopefully a software update from Apple will be forthcoming. Until then, however, the following fixes and workarounds may help:

For computers currently experiencing an input freeze, temporarily change the keyboard/mouse USB port to regain input Plug in an external keyboard into another USB port on laptops (or on desktops just change the current keyboard's port) and see if input is functional again. If so, then restart the computer. If not, and you do not have the means for logging into your computer remotely (either by screen sharing or remote login), then a hard reset with the power button will have to do.

To prevent future keyboard freezes, plug the modem into another USB port This will depend on the number of available USB busses in the computer. For MacBook (non-pro) owners, some have found that the port farthest from the firewire and power connectors seems to be the more stable one to connect the modem to. For some Mac Pro users, just changing the port has helped as well.

For MacBook Pro users, switching the modem to a port on the left side of the computer (the one that is on a different bus than the keyboard and mouse) seems to have solved the problem:

NOTE: The bus setup for each USB port can be checked by plugging a device into each port and checking how it's connected in the System Profiler utility. If possible, ensure the keyboard and mouse are on a different bus than the modem.

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