NRPE Connection refused or timed out Error

Every other execution of check_nrpe plugin results in “Connection refused or timed out”. It works the rest of the time. This happens even at the command line when Nagios is turned off (and therefore this isn’t a load issue). From what I can tell, this is a problem on the NRPE server side, right? Any ideas how to fix or troubleshoot?

I’ve also tried the version without SSL, same problem.

The problem was Windows 2003 R2. I downgraded to Windows XP SP2 and it works fine.