Ok, I think I may have figured out the issue. It seems the check_tcp I copied was 32-bit, and all of the other "checks" are 64-bit (the server itself is 64-bit OS as well. check_tcp: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, not stripped check_ntp: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, not stripped Seeing that I do not have any other 64-bit Nagios instances running I may need to run another install on a 64-bit OS just to harvest the "check_tcp" from it. <div class="gmail_quote">On Tue, Jul 12, 2011 at 10:03 AM, dOE <<a href="mailto:doepain@gmail.com">doepain@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> Hi, I inadvertently deleted/overwrote the "check_tcp" file in ../libexec. I tried copying the file back from another Nagios instance (same build 3.0.3), but when I execute it it I get a "No such file or directory". My permissions for the file are no different than other "checks_" in the directory. Is there something else I need to do other than copy a file from another Nagios instance? rwxrwxr-x 1 nagios root 76K 2011-07-01 13:47 check_tcp Thanks </blockquote></div>