> I don't use any fuse configuration on my program, and the *.inc is original.
> I use MPASM v5.20, and pbp 2.5
> I working with 20 MHz resonator.

PBP 2.50 defaults to the XT oscillator for the 18LF2620.
At 20Mhz you would need the HS oscillator.

If you have not used any configs, and the .inc is original, I don't see how it could work at 5V either.

According to the datasheet, you can go down to 3.0V with a 20Mhz OSC. So that's probably not the problem.

The only other configs that could affect the operation at low voltage is the Brown Out Detecter. But it defaults to 2V. So I don't think that's it either.
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