Right, i have been able to replicate the issues.
I really should have done this much earlier, so apologies
I upgraded ZoneAlarm, including Privacy, then fiddled about with loads of settings, and found the "ad blocking" option the culprit. Once i switched this off, i got past the 5 post issue, and I was able to see all of the thead.
i will now remove this banner from the forums for a couple days, and see the reaction of our "problem people".