I have a Toshiba G20 laptop. It has Windows XP Media Center edition. I bought a new Huawei E160G usb dongle. The dongle has a sim card in it and it is activated. The net is working. But the laptop does not allow me to use it. I had installed it in the laptop. The software that came with dongle shows good signal strength but internet fails to work. I have a a much older HP laptop in which it is working. I had removed unwanted programs from the system but somehow it is still not working.
It looks the dongle does not got proper driver in your system and that is why it is not working. Go in Device Manager and see whether you can find the device listed. If not then you will need to find a proper driver. Most of time this usb dongle comes with drivers and pc suite software in them. You just need to connect them and it is installed automatically. Later on you have to reboot your system and connect it. If that is also not working then remove it completely from your computer and re-install that from scratch.
It is a driver issue. I had got the same issue with a old usb modem. Windows does not has any internal drivers for that and sometime the driver which is present in the modem fails to work. You can find a driver from the official website also. It is not at all complicated to install it. Try to use it on different ports you are having in your computer.