Thanks fellas. Had a wee duke at the logs and then...
I had another go at it, but this time putting in the 7.56p2 patch that I found in the Members area, over 7.56p1 I had from last summer, and did some re-builds of posts and stuff and it seemed to work this time (with global php 5.4 engine)... thus far.
I've seen a lot of Forums recently and I have to say I still love UBB Threads simplicity and intuitive control panel... and the support from you guys here. ;D It's appreciated.