The only time I've had problems was when I changed computers and didn't reconfigure the datalogger, or significantly changed the program (did you look at another car with the laptop) and didn't reconfigure the datalogger.
You can try reading the program that you configured the datalogger with and then try to read the datalogger.
I've had similar problems and I've gotten into the habit of reconfiguring the datalogger at the beginning of each day at the track.
I took the box apart tonight and found a broken connection right where the interface plugs in, looks burned??? It was the white wire. I rigged up a jumper to extract the data...it worked! No I have to install a new connector.