Ok... not sure why this problem exists... all I can do is explain the issue and the steps I took to correct it temporarily...
After posting a number of articles in the default namespace today (around 20) I came back after a break to find that the main Wiki Namespace (the default one) had disappeared from my forum list... while the other sections (Headers, Templates, etc) were still there.
I tried to access the wiki direct from the URL ID... and got blocked access (much like the special pages bug I mentioned earlier).
I checked all the settings, and resaved them all, no difference.
I rebuilt the namespaces... no difference.
I resaved the forum and the namespace individually... no difference.
I checked the permissions, all showed as allowing me access.
I then manually saved my user permissions access mask (to yes rather than default)... I now had access.
I changed it back to default... no access.
I changed the Administrators usergroup to custom settings, while not actually changing any settings themselves... I got access.
Reverting them I lost access again.
I'm not sure what caused the change. It seems I can now access the special pages in the earlier thread... and that was the only thing I'd attempted to do different...
So... no idea what causes it... or even if it's a proper bug... but here's the report anyways.
