gps causing phone to continuosly reboot

Hi. When i use the GPS reciever with navigation or google maps the application will run for a few min before the phone reboots and then carries on rebooting non-stop every few min.
i think that it's a hardware issue, has any one had the same problem?
My phone is about 4 months old so i will be trying for a replacement.

Replacements are generally only done in the first 7 days after purchase.  After that, the phone needs to be sent back to HTC for repairs (which either means they'll flash it completely or replace the main board)

I've had the same problem when using google navigation and gps, the first few times my phone just rebooted then after that it began losing the gps lock. Not sure but I think it may be because it's using both gps and the 3g connection all the time which causes the phone to overheat and reboot or effect the gps chip in some way. I am testing out Ndrive and copilot as these don't need the 3g connection as the maps are preloaded.

Well after using copilot yesterday the phone lost GPS signal after 15 minutes then started rebooting whenever i tried to use any form of navigation, so what with that an a accumulation of dust halfway down and underneath the left side of the screen i'm sending it in for them to take a look at it.