Now I solved the problems.

The first thing was my JDM programming device, when I use:
@ DEVICE pic12F629, INTRC_OSC_NOCLKOUT
@ DEVICE pic12F629, MCLR_OFF
It is not possible to program the PIC again with my JDM or Velleman programmer.

I solved the problem by reading this: http://feng3.cool.ne.jp/en/vddctrl.html and by using a few components and a solderiron.

And Bruce thanks for the OSCCAL learning, I have used your suggestions to get the pic up and running again.

Thanks!

Regards
Gert