That error message is generated by a security check.
You can bypass the check by editing mainfile.php and changing:
define('XOOPS_CHECK_PATH', '1');
to:
define('XOOPS_CHECK_PATH', '0');
To find out why that check has started failing, you'd have to look at the code following that line and figure out what's going on.
Hi Dave_L...thanks for posting. I posted the same over at Xoops, and eventually got the problem sorted. View the topic thread
hereIn summary, turned out to be because of my web host changing the physcial path from
www.f3.org.uk to f3.org.uk.
Cheers
Ted