404 error page redirect not working

Upgraded to V1.5 from V1.3.9h a short time ago, upgraded by uploading the V1.5 files then upgrading the database, everything seems to be going good except the built in 404 page redirect is not working.

My old V1.3.9 install is still running on the same server and the built in 404 redirect is still working as intended.

Could someone point me in the right direction, I've been searching and searching but cannot find a similar problem at all on the forums.

Here is the error

Not Found

The requested URL /????? was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I know I can create a custom page in Cpanel but from past experiences zencart 404 redirect has always worked out of the box, have I done something wrong?