Transparent Proxy Blocking HTTP traffic

[Guest]

[JewKnowWho]

Recently the transparent HTTP proxy on the Endian has stopped allowing users to access HTTP pages. When they try they get

Access Denied

Access control configuration prevents your request from being allowed at this time.

in the HTTP logs there is the following

TCP_DENIED/403 2716 GET - NONE/- text/html

Having no luck with this at all, however when I flick the switch to non-transparent then it all works ok. However this is only from the server I haven't had chance to see if it works from the clients in Non-transparent mode.

Any ideas?