Have all updates been applied? This happened to quite a few people when the phone was first released and the updates since then resolved the issue. However, if you plan on rooting you may want to do that first, then flash an updated stock ROM. Current sw version is 2.08.651.2.
There were two updates released pretty close to each other. Once people applied them the problem was resolved and the os upgraded to Android 2.3.4. The thing is, the bootloader went from 1.4 to 1.5 as well and the only way to root is to use HTC's method. If you plan on rooting you may want to read through the Rooting section of this forum for more detailed information. If you are certain you don't want to root then go ahead and apply the second update.