A: The readings you have downloaded can't be fixed. To remove corrupted data from the instrument you need to do a Cold Start. Instructions for doing a cold start are in the GEM™2000 Manual.
A: Above 104°F (40°C) or below freezing, 32°F (0°C), your readings may be incorrect, or the instrument may otherwise malfunction. In extreme heat, the GEM-2000 screen goes black. If you are working in sub-freezing temperatures, you can use a hand warmer to keep the instrument warm. You might also keep the instrument inside your coat. In extreme heat, try to keep the instrument out of the direct sun. If its readings become erratic or the screen goes black, bring it into a cooler environment, such as your air-conditioned truck.
A: The cable that lets your GEM communicate with your computer is normally plugged into a "Serial" port, sometimes called an "RS232" port. Modern laptops often lack this port. You can purchase an RS232 cable from LANDTEC.