Your MCLRE is ON.
If you are using power adapter (not battery), make sure you have 100nf cap from MCLRE pin to GND. And I am not even asking about 4K7 - 10K res to vdd; Assuming it is already there.

And, if the osc is giving you issues somehow, then try OSCCON=%01110010.
And check OSC stable bits in OSCSTAT.