Lately I've been trying to track down a calculation problem in one of my programs. It's the obnoxious sort that sometimes happens a lot and sometimes runs for hours without issue. I've at least gotten as far as identifying what I think is the first place in the code the issue can be detected, but after putting in more extensive debug output to capture erroneous state without interfering with live use, the problem stopped again. I'll keep checking back with it over the next couple days.