Original Dutch article can be found @ HTC Desire Overhit.

A brand new phone with heat problems. Fortunately for other HTC Desire owners, but unfortunately for me, it is not a design flaw, just an individual product which has bad symptoms. It started a while ago and occurred sporadically, my volume down rocker hangs. My first thought was that it was related to a software bug. The first few times when it happened I was playing Line Up. (Great game!) So my conclusion was that it was the applications fault. Until it also happened a few times when I didn’t even touch Line Up, not even after a fresh reboot.

1) The Volume down rocker hangs. The volume rocker is leading it’s own life. When this happens it is impossible to turn up the volume, the volume will be lowered automatically. If you aren’t using a media application (Media Volume) this will result in lowering the Ringer Volume until the phone vibrates. If you are unlucky like me, the Volume Down rocker still hangs, so the phone is almost constantly vibrating. Rebooting the phone however is a bad idea. Since the volume down rocker still hangs, you will boot into the recovery mode.

2) Automatically reboots. This occurs mostly when the volume rocker is having issues. As soon as the volume rocker hangs, and you turn off the phone, it will crash.
This problem can often be reproduced once problem #1 has occurred. I can even reproduce it manually: Push and hold the volume down rocker, even when the phone vibrates. Turn of the screen. The phone will crash.

3) Battery “overheating”. That is what I call it, because above problems only seem to act when the battery temperature is above 32 Degrees Celsius. And this temperature is reached quite fast, so you have the problems quite often. It is for example impossible to use the phone as navigation while charging.