Help: Evo reboots during call if using Sprint Nav

[random omen]

If I am using the factory Sprint GPS software and make a phone call, the phone call will go through for a few minutes but the phone will inevitably reboot mid-call. Before the phone reboots I can swap back/forth between the call and GPS program without a problem. Even if I don't swap it still reboots.

Phone does not reboot if just making a phone call, or if just using the Sprint GPS software alone.

I do not have any task killing software nor is the phone rooted.

Any ideas?