Re: relaunch the computation?
Doesn't sound that hard to me. At periodic intervals (say, after each millionth instance), open a temp file, write the instance and the current result. If it's ever restarted, re-open the file, re-read the instance saved and the result at that point, allowing you to resume. Two rather basic routines, actually. And if the computer crashes or blacks out, the maximum loss, provided the temp file is kept healthy, is shy of a million instances which in a task requiring more than million times such would be at worst a mild headache.