ntlm_auth problem

Hi All. I have setup up a VPN server using FC4 and Poptop using freeradius for authication via a Windows DC. As far as I can see everything is setup correctly, however it fails to authicate any users when a login attempt is made. It is logging the following error message in the radius.log file: Tue Nov 22 22:01:47 2005 : Error: Exec-Program: FAILED to execute /usr/bin/ntlm_auth: Permission denied I have checked the permissions on this file and everyone has permission to execute it and if I execute it manually from the command prompt I can authicate users without issue. Anyone have any ideas what the problem could be. Thanks in advanced. Andrew.