Why is it I can open my own thread but when I attempted to reply to another thread I get this:

"canadamanada, you do not have permission to access this page. This could be due to one of several reasons:

Your user account may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation. "

I just hit the REPLY button and this is what I got.