Yes i have a protection relay diode.
I resolved my problem by hardware, i put a 10uF capacitor between +5V and GND. It's possible to resolve this with software? My doubt continues...
What i dont understand is with PIC16F505 i have reset problems and with PIC16C505 i don't.
I saw datasheets i didn't see anything relevant different.

Maybe PIC16Fxxx is more sensitive to turn on relay than PIC16Cxxx!!???