As I would have never expected it, obviously the ubuntu team produced an embarassing bug with Ubuntu 9.10 "karmic koala": the popular USB data dongles for mobile broadband internet connections stopped working.

masses of users around the world are posting bug reports and complaints that their data sticks aren't recognized by karmic any more -- the same experience as I made. 

 I am using ubuntu on my home notebook in the local LAN, where the problem doesnt really affect me. But additionally I was so happy when Ubuntu NBR was released with 9.04 - I am using my Asus EEE PC Netbook day by day where I depend on the USB data stick to get connected. And I MAINLY use the netbook to stay online when being on business journeys - mail and internet. So it is a major problem that my USB-data dongle, a huawei e169g, stopped working after I installed the brandnew ubuntu 9.10 NBR. (which btw is pretty cool).

 after trying around and googling I found the following combination of actions to solve the problem for me:

• insert a micro SD memory card into the huawei e169g
  
• plug in the huwaei usb dongle into the pc,notebook,netbook
• wait until 2 drives are mounted: the "cd-rom" which is buiit-in and contains windows drivers for the huawei, and the second drive which represents the micro-sd card
• open nautilus and "safely remove" the micro sd card (i.e. unmount) - both mounted volumes are unmounted
• after that open a terminal and type:
• sudo modprobe -r option
• sudo modprobe -r usbserial
• sudo modprobe usbserial vendor=0x12d1 product=0x1001