Once the V800 is me crashed right in training. After about 20 kilometers uphill, I wanted to check in altitude and had to change the training view. Then everything is frozen and the V800 responded to nothing. By pressing buttons all I managed to initiate a reboot. The functionality was thus given back. However, my training had gone up to this point. Later lkam even when not syncing again. Too bad. But each computer may get stuck once. Unless it happens more often it was forgiven him :-)