This is one of the common errors you get when you use your USB modem or your wireless USB modem on a windows operating system. In simple words the software installed for your USB modem is not able to detect the drivers for your modem. Well the solution is very simple. Close the connecting software and unplug the USB modem from the USB port, plug it back again and wait for the software to initialize or open automatically (for the auto-play to happen the plug and play service on your computer should be showing as started) (on win vista if user account control is ON you may get a pop up with an option to auto-run, if you get the popup click on auto-run) the software will open automatically and you are now ready to connect to the internet as it will detect the drivers.

If incase you still get the same error device does not exist or unavailable then there may be an exclamation on the USB mass storage device under Universal Serial Bus Controller in device manager.  To get to device manager you have to go to your control panel switch to classic view (in windows vista you will find device manager as one of the icons in the list) (in windows XP you will have to open “System” and then go to the “Hardware” tab, you will find device manager as one of the buttons) right click on USB Mass Storage Device and select “update driver”. When the wizard opens select the manual option and tick the box which has the option include this location in the search. Another window will open where you can select the location of the driver( My Computers / Local Disc C / Windows / System32) single click system32 and then click Ok. Now your back to the previous page click next and it will start to find and update the driver. Once the driver is updated the rest of the drivers under DVD / CD Rom drivers, Ports and Modem will follow. The software will open automatically if not open and you are now ready to connect to the internet.