I've never used nrpe, but in reading the install notes I can only wonder, did you make the necessary changes for it to use inetd instead of trying to use xinetd?
Referring to this:
b) Assumptions
These instructions assume that you are installing the NRPE addon on a system that supports TCP wrappers and
has the xinetd superserver installed. Most modern Linux distributions and Unix variants have these installed by
default. If you have an older system that runs inetd (instead of xinetd) and/or does not support TCP wrappers, or
you want to run the NRPE daemon without inetd or xinetd, read the following files for information on installing the
addon (both are found in the main directory of the NRPE distribution):
â README
â SECURITY
"The difference between me and you? I will read the man page." and "Respect the hat." and "You could just do a search on ITRC, you don't need to start a thread on a topic that's been answered 100 times already." Oh, and "What. no points???"