Well crap, spoke too soon..... yeah made no difference....
" *** OCTANE API MSG: Tried to access null item
*** OCTANE API MSG: Tried to access null item
15124: Fatal error: Segmentation fault
Crash log saved to C:/Users/DESKTO~1/AppData/Local/Temp/houdini_temp/crash.hairFur_013.DESKTOP-TS9395C_15124_log.txt"
This pops up and suddenly BOOM! crash to desktop. Man it's so annoying.
Okay so I think I might have finally figured out what the cause was, and as suspected after a while, it obviously wasn't actually Octane crashing because the log clear showed that when it ran, it finished and died before it could run again.
Basically I think basically it was a memory instability as a result of cpu overclocking, I had played around with different settings recently, without any problems so far that I was aware of, but I realized that the BLCK was at 101mh (100mhz being default and usually recommended). Anyway running a 2990wx with very sensitive memory and speeds, I am sort of quite confident that this was the cause, which also explains why it would be random, because every so often the memory would just fail, but not enough to crash the system, just not stable. this also would affects PCI-E and everything else... a bad idea which I already knew, but I forgot it left it there.
Anyway, long story short, I have now changed this and so far I have rendered 2 sample files, without houdini crashing during sim/playback and Octane rendering 60 frames of one and is now up to frame 21 of the project that was the problem initially, which usually crashed between frame 4-9. So far I haven't seen the weird Null error either, so I wonder if that's related... Anyway I will let it render and update if it is actually stable or if there is more to it.
just want to say thanks for trying to help @juanjgon I can't imagine how difficult it must be at times when people just rock up with "it doesn't work, and there could be 400 reasons as to why"
btw can't WAIT for 2019.1