Interrupt mystery - need some guru help

[xnihilo]

There's only one riddle...why haven't you read the section I specified earlier?
It's right there in the datasheet...Section 4.2.3, 2nd paragraph.

I did.
Never mind, I will ask in another forum.

I think the problem comes from the fact that my RA3 is linked to nothing. I will connect it to 5V via a 10K resistor.