I had the same issue for 5 days, every time i oppened a gps app my phone would reboot
called up htc, they had no solution, called sprint the tried everything and couldnt fix the problem. They even had me do a hard reset & the problem still occured.
i did some research online & its a growing problem among evo users, here is the fix.
Do not factory reset your phone, the problem will comeback, resetting your sd card wont help either.
This is the fix i fould online & it works, after 6 days still no rebooting.
I found that only clearing out the GPS unit using hash code ##GPSCLRX# and then inputing your msl code which you get from Sprint. Here are the steps if anyone is intersted, best part is no hard or factory resets needed. Also no app troubleshooting. The only part that sucks is you have to call and speak to Sprint and they don't like giving out the unlock code. I told them exactly what I was going to do and they gave it to me. I did the whole Sprint repair as well as new phone senerio and I still had the issue return. Factory and Hard resets did nothing either. It always came back within 24 hours.
1) Call Sprint and retrieve msl code.
2) Open dialer and press ##GPSCLRX#
3) When prompted input the code from step 1
4) Phone will reboot in 20 seconds
Hope it helps, your welcome!