Hello!
Ooo, that looks bad doesn't it. Same happens for me from the main predecimal.com root (without /forum/ etc).
Sorry for being slow with this. I was away in GB for some of the time. The forum software is quite old now and could do with an update. The problem is, it requires a newer version of something in the background (php), which isn't normally an issue, but I know that other stuff won't work with the newer version.
I think the way forward is to turn predecimal.com into just a forum. I don't really buy/sell coins at all anymore as it became less practical since brexit and also I wanted to concentrate on on the books and app, as they are so much simpler to manage, which is what I've been doing for some time. It should be possible to separate the forum, have it work from the root predecimal.com/ and upgrade everything in the background so that it all functions properly again. There may be some issues along the way that will need to be ironed out, but I don't really see an alternative.