I think it is unlikely that the hard drive is the problem. The 10v is fanless, so it relies on a thermal compound between the top of the processor and some metal heat sink. When you say you use "a cooling pad", what do you mean? A base with a fan? Because if it's one of those "heat absorbing" pads, my experience is that they stop working fairly quickly.
Have you checked to see if any programs are using lots of CPU? Click Start, and in the search menu type "Performance Monitor". Click on the entry when it appears to run it. It will tell you how much of the CPU is being used. If it's more than 30% while web browsing, you have a problem.