it's weird for sure. i have like 1/100 users eventually report weird interface issues. maybe it's just a crap interface with a counterfeit chip dying or bad wiring in the car. i would consider doing one of my DIY interfaces and just trying it to see if that works instead. go on ebay, buy a FTDI TTL interface, hook the RX and TX wires together, and connect them to the data pin, and ground to the ground. instant 10 buck ALDL cable. i developed flashhack entirely with an interface like that. the wires were literally twisted together. it never failed.