as you have figured it, this error comes with SSL encryption … so, the “best” way to avoid any troubles is to disable it
So yes, that’s the last resort way, but when you’ll be bored trying to solve this problem, re-compile your nrpe with option “–disable-ssl” and problem solved
in the meantime, you can try to do a “ldd nrpe” (and also a “ldd check_nrpe” on the server, but that shouldn’t be a problem if only one host is affected) to see if all the librairies are present.
You can also try to re-install openSSL on the client …
but still, if all fails, just use “–disable-ssl”