This is help and support forum only. Your comment is neither helpful nore supportive.
Can't block people.

Actually, no. It is lying and if I could, I would block you. Since I cannot, I request you get off my forums or I will report you for harassment.

Your forums?
I think there is a limit to the number of people you can have blocked at one time. Maybe go through your Blocked list and see if any of those accounts are now closed or deleted and unblock them to make space

Thank you Baron but the problem is still persisting...I have removed from my block list people who have had their accounts closed and still cannot block people.

Hahaha...
Actually, as it is a forum I've started, any one I block is prevented (or supposed to be--I've had glitches in the past) from posting in ones I have started. Seeing as the current glitch is that I cannot block you, I suggest you flee from this forum before it gets problematic for you.
For some reason, I cannot block people any more.