If you install it from the deb it should work as user instead of root. If you run it as root, it will create files in /tmp as root which it can't access as user so will not run until they are removed or after a reboot. Remove /tmp/gpsd.log and /tmp/minigpsd.pid if they exist (as root) and it should run as user. If not, try "strace minigpsd" as user and past the last dozen or so lines.