SOLVED! PM Error: You are not authorised to read this forum

[RealBlackStuff]

Got something strange happening!
If you send a PM to someone, it also sends the link of the post from which you send that PM.
If you get an answer (or several answers if the PM-ing continues), in the new forum you can now see the whole conversation between you and the person you PM'd.
However, when I scrolled down in the conversation, to check again about what post I originally PM'd,
I got an error message: You are not authorised to read this forum. when I clicked on the link to the original post!

After digging deeper into the system, it turned out that the thread/post giving this error had been LOCKED by a mod/admin.
And it was also moved into the mods' archives, so no further public access. Ah well...