Firstly, loving this forum software.
However I've got a problem I've no idea how to resolve. As admin I can create posts and attach files. When I test as a standard user I can create a post and save. However if I try to attach a file and save I get the following:-
A potentially unsafe operation has been detected in your request to this site.
This comes from your Security plugin, you should configure it to ignore this kind of activity. This issue can not be fixed from wpForo site, because it doesn't come from wpForo.