I have modified the site's code to change the behaviour of url's in the body of messages.

Under phpBB2.x url's would launch in a new window. In phpBB3.x this was altered to opening in the same window and therefore navigating away from the forum. This has now been modified to behave like it did in phpBB2.x so all url's should launch into a new window and the forum should continue to appear in its original window at all times.

Please note, the effect is not retrospective - previous message bodies will still open as they did before but all new postings which contain url's should be affected (and edited messages should re-process on submit to work like the new format).