In Perth, Western Australia where I live, summer temperatures often reach 35C, and during most summers we have at least one "heat-wave", and sometimes two. During a "heat-wave" temperatures get above 40C for about 6 to 7 days in a row. I have noticed that my laptop computers, and my friends laptop computers, do NOT fail in these temperatures; they keep on working just fine.
I have a few Thinkpad laptops, and an Acer netbook that I keep in my shed outside, where the temperature is often above 45 C in summer. Sometimes I use the laptops in the shed at 45C but I feel like I'm ready to pass out long before the laptop does. I have never had a laptop fail, or stop, due to using it in temperatures of 45 C.
In the north of W.A., on the edge of the Great Sandy Desert, temperatures are above 40 C EVERY DAY from about October 15th onwards, until about the middle of March the next year. Some days get to 49 C in the shade. For people who work outside, in the sun, their computers can get too hot to hold, but they keep working in these sorts of temperatures.
Remember that most laptop components were soldered onto the motherboard using molten solder at more than 200 C, and the temperature of molten solder did not damage the components.
Temperatures at about 75 C might warp the plastic that the computer case is made of, but it will not damage the internals.