Yep, sounds familiar.<p>At Imagen (a Stanford TeX project spin-off started by Knuth's sidekick Luis Trabb Pardo, building the first typesetting-capable commercial laser printers using, at first, wet-process Canon imaging engines (LBP-10)) in the early 80's, we used the same Sun board (Andy Bechtolsheim, the designer, was a consultant for us while he started up Sun).<p>I wrote our own "real-time OS" on the bare 68K Sun hardware (first time I'd ever written a full (if simple) OS from scratch), and remember fairly vividly the hard-knocks learning experience about race conditions just like the one he describes here. Running for hours or days without error and then crashing randomly--nightmare time.<p>Luckily, we also had an ace hardware guy, Kok Chen, from the Stanford SETI project, and he and I and the logic analyzer would run test setup and lie in wait for the condition to show up, then look back in time at all the (Multi)bus transactions to see what actually happened. (Kok later moved to Apple and became a distinguished engineer, one of very few folks who could work on whatever they wanted.)