I'd never heard of Firefox (other than a Clint Eastwood film I think) before today and now this is the 3rd thread I've seen it referred to in!
It could be the pop up blocker. The ad problem has only just started, and in the last few days when I try to open a PM it now tries to block it, which I don't think it did previously. PC did a virus update the other day so it might have changed something. I'll check if the same is happening on the upstairs PC out of interest, but obviously it's not a problem at 'your' end so that's fine. As long as the link is working (for everyone else!) that's OK.
Cheers
