Hi lionstorm
I just want to clarify something:
I take it that you mean that the 64M SIMM will work alone in either slot, and that mixed with the 32M SIMM it won't be recognised. Is that correct?
The random crashes are probably due to heat.
When you say you 'stick a heatsink on', does that mean that you do it in a proper fassion? I.E. keep it held down flat, and use heat transfer compound?
Have you considered using a fan? That might be the best option.
Two tips:
-Clean everything, make sure all contacts are clean.
-When the machine is running, feel different areas for excess heat.