As an update, in case anyone has half a clue as to what's going on, the error is;
Application popup: Jedi Knight 2: jk2sp.exe - Application Error : The instruction at "0x004ac834" referenced memory at "0x0edaf000". The memory could not be "read".
Tonight I've gone through the obvious, the dubious, and the clutching at straws. Todate tactics have been;
Video, Sound, Via 4-in-1 Driver reinstall (all latest), DirectX 8.01, and JK2 reinstalled also.
Cleaned CD, swapped drives between DVD / CDR etc
Bios tweaks, up/down on AGP aperture, and AGP 2x mode support on/off, and even as far as moving the Win2k swap from c: to d:, boosting swap max size etc but to no avail. The game bombs out as the level loads leaving me with the brightest desktop known to man.
(NB: Also bombs out if I call the map direct with map ns_hideout, basically 1/3 of blue bar then death)
All suggestions gratefully received cos no effin idea, and now streessed and having withdrawal symptoms