Another thing to check, as I had this happen to me. There is a safety switch on the brake linkage that gets surrounded by grass clippings and dirt build up. The switch connector is on the right side, closest to the engine, under the fuel tank. I had to remove the grass mat that had built up, and took off the connector and blew it out with air. Apparently, being out in the rain or washing the mower got the grass mat wet, which kept water around the connector and shorted the contacts. Mower stopped dead while mowing, and I thought the transmission was bad. Turned out to be the switch, which was still good. I love 0 cost repairs.

The fan that blows the cold air to the freezer is running irregardless of whether the door is open or not. Also, the fan may be old (You didn't say how old it is), and making noise due to worn bearings. You probably don't hear the fan when the door is closed.

The seat switch is not the problem. There is a switch above the brake linkage underneath and to the rear of the engine. The actual switch is on the right side, underneath the fuel tank. Grass clippings and dust tends to build up around the electrical connector, and if the mower is out in the rain, or you wash the mower, the water tends to short out the connections. The switch may not be bad (mine was OK), but the grass mat that has collected has to be removed, and the connector removed and blown out with air, or whatever. (This same condition also causes the mower to stop moving while the engine is already running) I guess it depends upon which connections are shorting on the switch.

Check backup battery first. Weird things can happen once they go dead. 14 years is a long time for one of these to still have any voltage.

Did someone change the belts? If this happened by itself, I would look at the belt tensioner pulley (idler pulley), being frozen. (Not the wheel itself, but the arm that it's connected to, make sure it can move back and forth) WITH THE MOWER OFF

It's a very old unit. It can only run 32-bit programs and Operating systems. About the only thing you can do with this is remove windows and install a Linux operating system that will run on 32-bit systems. Think Puppy linux, or something similar. Google 'Linux for old computers.' Have fun.

Is this one of those continiously variable speed transmissions? Not the single-speed-at-a-time shifters. Then it could be fluid loss at the transaxle. (Just like transmission fluid) I've never had to add fluid to mine, but I'll look tomorrow. If it's not that kind of transmission, then the problem would be a lot simpler. Drive belt is old/loose, along with possibly old/missing idler pulley spring.

If they worked before and they don't now, one of them may have developed a fault. Or maybe there's some crud on the contacts of either the ram sticks or the slot. You should take a good close look at the ram slots and the ram contacts. If there's any foreign material there, CAREFULLY lift it out. For the ram, any dark spots or marks on the surface should be removed with a SOFT eraser. Do not ever use an ink eraser. It'll remove the plating. Use a pink eraser or a gum one. If that doesn't fix it, then the stick may have developed a glitch. Run a memory test from bios or Google memtest86. It takes a while, but you have to let it run for at least one full round. Good luck

I also had one of these that sat for a long time. When started, the same thing was happening. Turns out the CPU fan had frozen from disuse. Replaced fan, runs fine. (If the fan is not running for any reason, the computer shuts down)

if the fuse is OK, take a look at the actual grid on the rear window. Sometimes, from wiping the glass, or objects rubbing against the glass, the line on the window, (those lines are the actual electrical resistors that warm the glass), will get a break somewhere. It doesn't take much, because thos lines are just like a wire. One break or missing stop, and the circuit is broken. Doesbn't work. Kaput. If the break can be seen, you can get a bottle of resistive repair from the auto store. Just brush (carefully) the liquid on the missing spot, to re-complete the circuit. Don't get messy, or think that more is good. - It's not. You just want to re-connect the line, (only) where the break or gap is. It usually takes only 1 tiny dot to do the job. Good luck.