First off, this thread is from 2007
However, we will forgive Mylo124/Liz, as it is their first post, for resurrecting the thread.
Now, they dont generally experience temps hot enough to burn them in the wild, its not something they really have to worry about.
Thus, no need to evolve any sort of trigger for whether or not their flesh is cooking. Thats the basic reason this type of thing happens.
If you place a frog, in luke warm water, and crank the heat, it will boil alive before it hops out, because it doesnt know any better.
If temperatures are not monitored, and kept in check, the chameleon will cook itself.
It doesnt matter how far away the basking lamp is, that is variable.
What matters is that the highest temperature that the chameleon has physical access to, is constantly monitored, and kept at a reasonable measurement.
That point for this particular chameleon, would generally be no higher than 95F-35C. That should be the highest temperature the animal has access to, period. Even if it can only access it by climbing on the screen, upside down, and really pressing its belly to it.
At the same time, the chameleon should have access to a temperature gradient, from the (no higher than) 95F-35C, all the way down to (around) 75F-24C.