Q. By referrer issues.
Yes, there are cases where the http-header referrer information is not correctly passed to the server.
It could be because of an option in a browser, a firewall or proxy stripping out the header, a browser not even having the capability.
One common example is the WMP browser, which standalone does not pass the referrer to the server, however if embedded in IE or Firefox it does. See here.
In the AuthentiX installation directory there are some copies of debug.asp.
Take one of these and put it in an unprotected directory on the target machine. Use the browser method in question to access this file via http. If there is no referrer information there, then none is being passed to the server.
If the referrer information is required for access, but the referrer information is not passed to the server, then the browser will be blocked by referrer.