Interestingly, anyone using the stock OpenACS 3.2.5 config file avoided this problem, as MaxOpen and MaxIdle are not defined as 1B; they're in fact not defined at all -- those lines were commented out. Anyone know why that was?

In any case, that presumably is why those of us running OpenACS 3.2.5/AOLServer 3.3.1+ad13 systems have been OK, while those with problems were running ACS-derived systems prior to 3.2.5 -- in which MaxOpen and MaxIdle were defined as 1B.