.... till I hit the Esc key. It ran undisturbed for better then 4 1/2 hours.
Last time I used this program was many years ago but I do not recall it running all that long.
BTW, testing 1 gig of Kingston Hyper X 2700 mem.
Memtest86 continues executes indefinitely. The pass counter increments each time that all of the selected tests have been run. Generally a single pass is sufficient to catch all but the most obscure errors. However, for complete confidence when intermittent errors are suspected testing for a longer period is advised.