Br. what is the model of your dongle which you flashed sometime's when flashing occur's via computer silently virus creeps into that dongle.
Sometime's by the person himself who did that job with his infected machine...cos some of these phone technician's is not exactly aware of a computer they only know to flash and install phone software's with different gadget's that only is capable with very few expert's..
Recently this kind of problem was faced by a person who bought a dongle and the it didn't work but when I plugged into my 100% viri free computer ...msg a virus in the autorun of that dongle (after flashing - how come...)..