Edwin,
> We are running postgresql 7.2.1 on cygwin on a Windows 2000 box with 2GB
> RAM. After more than 3 or four clients connect, we get this error repeated
> in the log and the database refuses more connections.
Not offhand ... I don't use cygwin, and this sounds like a Cygwin problem.
Have you tried the Cygwin mailing list?.
--
Josh Berkus
Aglio Database Solutions
San Francisco