first off, Merry Christmas and happy new year to everyone on PB forum...

ok, this seems to be an ongoing problem i keep having with the 18F4550...
Various programs i've done to do different things... i always seem to have a problem getting the pic to run. I have to keep disconnecting the power and reconnecting untill it does.
When it doesn't run i seem to get ether intermittent repetitive (the same thing over and over and LED flashing rapidly etc) activity like the pic is resetting after a fraction of a second. or i get a complete lockup.

And yet, i wrote a program for a friend for the 16F610 and it runs first time without issues. same program (diferent fuse config) recompiled for the 18F4550 refuses to run most of the time.

But then when i get it to run, it happily runs for days...

Supply voltage, well, i've ran from 5V regulator (7805CV) and direct from Li-Pol battery (~3.8V)

Below is the fuse config and the osc setup. have i made a mistake somewhere?
Any advice appreciated.

Code:
@ __CONFIG _CONFIG1L, _PLLDIV_2_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
@ __CONFIG _CONFIG1H, _FOSC_INTOSCIO_EC_1H & _FCMEN_ON_1H & _IESO_ON_1H
@ __CONFIG _CONFIG2L, _PWRT_ON_2L & _BOR_ON_2L & _BORV_3_2L & _VREGEN_OFF_2L
@ __CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_256_2H
@ __CONFIG _CONFIG3H, _MCLRE_OFF_3H & _PBADEN_OFF_3H
@ __CONFIG _CONFIG4L, _STVREN_ON_4L & _LVP_ON_4L &  _ICPRT_OFF_4L & _XINST_ON_4L & _DEBUG_OFF_4L

Define  OSC				8						' Set clock speed

OSCCON = %01110000
Thanks