All, I think I can finally report what was causing my intermittent NeXT cube "unexpected kernel page fault" crashes. Up-time is now over 240 hours and counting. The problems were heat, and bad ventilation. The short story is, I had the fan reversed (to blow into the cube) and had a very leaky enclosure as the first step on the cooling air path. This was due my installation of a floppy drive looking out through an optical-drive-sized aperture in the front of the cube. Clue for NeXT cube owners: seal up unused apertures and air leaks in the front of the cube. The air needs to go into the drive bay, down into the power supply, out into the motherboard bays, then out the bottom of the machine. In my case, sealing apertures alone didn't do it - I ended up putting the fan back to its original flow direction (exhausting from the cube, so that the CPU board gets the cool air *first* as it is pulled in I also sealed up the optical and floppy apertures completely, using blocks of black foam rubber (which I'll pull temporarily in order to use the drives as needed). This may eventually cause trouble with the optical or floppy, YMMV and I don't have any long-term experience with it. I'm hoping it will minimize dust build-up in the optical, which is the original well-known reason for reversing the fan. Hope this is helpful, and many thanks to the list members that helped me with hard drives, parts, etc. The "long story" of all the stuff I tried and why I tried it is available on request, for the next few weeks at any rate (until my WORN cranial storage system has purged the details....). - Mark