General help

Hi all,
Here is what I am facing: Some students (we call them members) can't read new posts. When they click on the new post to read it, they get this message: "You do not have permissions to view this post" in a pink box. Don't understand why and need to fix this ASAP.

Also, students don't have access to other student's profile, and can't figure out why. Just don't know where else to look.

Ideas are welcome!