Hi,
first time I reading Your problem I must remember to my problem last Year with the use of TEMIC 80c32 in our application.
We found out, after reading the excellence application note from philips "use of x-tal on 80xx" that it´s some time a problem with the x-tal driver in the controller (small design).
The function of the oscillator of the TEMIC was in depend of the vcc. Increase of the voltage up to 5.2 volt makes the µC running. We inserted 22 controllers (all TEMIC) and found, that some works with 5.1,5.0 or 5.2; we changed the values of the capacitors to, with the result, that some works with 15pf, some with 30pf and some with 50pf; since this time we use philips processors.
Regards
Werner