PICkit 1 and 12f675 - micro broken ?

Hi

I am a newbie, I am using the good PICkit 1.

I am programming 12f675, taking it from the pickit board to the breadboard, test, and come back to the pickit board.

Unfortunately after about 40 cycles two micros seem broken: from MPLAB IDE I do "Program Device" and

- sometimes a "Verify device" reports "Verify failed... Error in Configuration memory."

- even if Verify is ok, I put the micro on the breadboard but it doesn't work.

The PICkit and another 12f675 work fine.

I asked about tweakings, because somtimes the "Configuration Bits" go weird: Oscillator changes from "Internal RC no clock" to "External" Watchdog Timer changes from "Off" to "On" Master Clear Enable changes from "Internal" to "External" ...

I set the bits to the original default, but I am not sure if/when the MPLAB IDE send my settings to the micro.

3) Do you have any suggestion to avoid too much stressing the micro while developing the first apps ?

I am a newbie, I have only the PICkit 1, Windows XP home and a very old second hand HP 180 oscilloscope.

ciao, Massimo ITALY