I experienced the same problem on both my wife's 2002 500 XC SP, and my 2002 800 XC SP on one night in St. Germain last year. We were coming back from a 250 mile day, and in low snow conditions. My wife's 500 started to run hot, and shut down from overheating. My 800's hot light popped on a few times, but off trail snow colled her down. After the 500 cooled down a little, we switched sleds, and the 500 was fine, while the 800 ran hot. We kep switching to get back the final 30 miles to camp. I have been told to try softer springs (she weighs 110 soaking wet), a larger snow flap, change TPS, Adjust timing, add a Polaris rear radiator, and/or a SLP nosecone radiator. Polaris should step up and take ownership of this problem.