Not saying this is your problem...but sometimes the datalogger gets, for lack of a better word, corrupted. I used to have to reset mine about twice a year. I'm talking the full reset...power down the console, remove batteries, remove datalogger for 20 minutes, then re-assemble. For whatever reason WD can't find the timestamp in the logger and it just loops. I've found the best thing is to forget about the lost data, reset the datalogger, and continue on from there...