We're having a problem over at dyndns.org that, when we're doing huge amounts of UDP activity (DNS queries) in one Perl program, it's somehow "losing" it's ability to send || receive the UDP in the middle. It's not always the case, and it only happens when the amount of UDP gets over a certain threshold (that we haven't determined yet), but it's a huge pain. Anyone with suggestions for tracking this down or fixing it would be gladly received! The systems we're seeing it on are running FreeBSD, FWIW, and Perl 5.6.1.
