You are in luck, I just fixed mine... No you are not going crazy and unless you know the right search wrods it is very hard to find the right information when searching the internet. I know this from my experience! I am going to post this on a few more forums so others can find it too...
The freezer has two devices called thermistors that sense the temperature inside. One is usually at the bottom of the freezer and the other is behind the back panel inside the freezer mounted to the evaporator coil. The one that is on the evaporator is probably bad. Typically your freezer goes through a defrost cycle once or twice a day depending on how much the door is open and how long the compressor is running (the controller board monitors this type of stuff). During the defrost cycle, there is a heater that gets energized to melt any ice from the evaporator coil. Once the coil has warmed up, the thermistor at the top of the coil starts to heat up and this tells the controller to shut off the defrost cycle. If the sensor goes bad and reports the temperature as being lower than it really is, the defrost cycle keeps going until eventually it hits some maximum time out and the controller shuts it off even without the sensor reporting that it is warm enough. My defrost cycle seemed to run about 45 minutes before it timed out. When this happens, ice starts to melt and drip down all over everything, ice cream gets soft, frozen juice starts to melt. After the time out, the defrost turns off, the freezer cools down and everything freezes again (ice too, but now it is in a big block).
Thermistors are universal, so they will work in all makes and models. I bought mine on Amazon for $3.30 plus $5.95 shipping.
Check out the following links and it should become clear:
excellent explanation with specs and pictures.
How To Check A Thermistor On Ge Refrigerators
Video if you need more hands on...
Hope this helps. DO NOT LET anyone tell you that you need another computer board (also available at Amazon for $110 including shipping) before they show you the resistance readings! Seems like many want you to replace the board before they even check! That is what the repairman who came to my house did, but that is a very upsetting story that I won't share here! My evaporator thermistor was reading 107 kohms when I checked it... It should have been more like 47.