Comment 18 for bug 469376

I have not tried 10.04 yet, but probably will in the next week or so.
 If I had to guess right now I suspect what you are experiencing is an
artifact of the somewhat publicized Ubuntu elimination of HAL in 10.04.

In 10.04 Ubuntu totally eliminated the Hardware Abstraction Layer (HAL).
   The ozerocdoff function for Option cellular modems is dependant on
HAL to at least some extent. In your second attempt by electing to
upgrade to 10.04 from 9.10 rather than a fresh 10.04 install you
probably left enough residual of the old 9.10 HAL laying around so
ozerocdoff was still working after the upgrade.

Some 9.10 to 10.04 breakage is to be expected. When I do try 10.04,
the first attempt will be to run it from a totally clean fresh 10.04
install with nothing extra remembering to use the Ubuntu native function
they have now to "supposedly " replace ozerocdoff ( usb-modeswitch ).

The trick is going to be to get usb-modeswitch to disable the zero cd
before the stupid and never to be sufficiently damned Gnome
Modem-Manager function comes bumbling along and locks the computer.

The problem has always been Gnome Modem Manager has never really
understood how to correctly turn off the "zero cd" function on Option
Cellular Modems while blindly and incorrectly assuming it knew
everything needed to correctly identify, initialize and control any
modem device. This faulty assumption proved to be disasterous.

So I will try it with just Ubuntu first, and after exploring every
reasonable means to make it work, then I expect to be forced to go back
to the Pharscape HSO packages and tweak that until it works.

Good luck

Pat Hickel