My display screen during the

My display screen during the ride will sometimes go blank. Then I cut it back on, but also have to hit "START" again. Display shows all accurately, but last 4 rides or so when I upload informtion to my computer, it give inaccurate average speed! I usually only avg. 17-18, and it had read anywhere from 22-29 for my avg. speed, which definitely is not correct. What can I do? Do I need to ship it back to you? I have had it less than a year, but it was a gift, so I will have to track down receipt, if still available! HELP!!!!!!!!!!!!!11