AVR-Chat

Javier,

> The thing comes when a tie an external
> voltage source to the reset pin (ex. an ISP programmer). Everything
> seems to work fine, even the reset circuitry, but as soon as i take
> out this external reset source, the chip halts. I dont have a clue
> about what this could be.

Try connecting a pull up resistor between the Reset pin and the 5V supply,
that should do it.
You can't leave this pin floating, it needs to be connected to a 'high' for
it to work.
If you plan to use the ISP sometimes then use a 10K resistor and all will be
well.

Paul