I just got this error today out of nowhere. I was not even working on my laptop when my 3g USB dongle was not recognized. I tried every trick in the book: a clean restart, I removed all USB drivers and reinstalled them, reinstalled the mainboard chipset drivers. Nothing worked. Until I got the idea to shut down, remove the battery and unplug the laptop from the power source. After the restart, everything worked just fine. A miracle, right? The simplest fix in the world.