I hesitated to post code before because it's several hundred thousand lines (well, that and some of it I wrote on no sleep and I know blows chunks, aesthetics-wise ;). Would the preferred Monk-friendly approach be:

(a) Post a URL
(b) Post a snippet showing just the loop control and what I think are relevant portions (which may not, in fact, be relevant)
(c) Something else entirely

I am, as soon as I have a a system available to me, testing on a Linux box as well for comparison purposes. I will also be testing paring down the tallying piece and re-testing to confirm that the problem does not occur unless the hash is growing, and then add bits back in a bit at a time to see whether I can identify anything specifically problematic.