Yea the same thing has been happening to me. I have to click add reply and then click on Piriform home and then the reply is there but if I click on Add Reply 2 times, it double posts.
EDIT: Now there's a cursor somewhere in the forums except for when you're posting. I just noticed it now. The forums have been acting kinda freaky lately.
It's the slowness I think of the forum. If you wait several minutes for posts and PM's to actually go through they eventually will.
A good trick I've been using is if you don't want to wait and wish to go elsewhere in the forums is to open another browser tab whilst the other one takes 100 years to finish what it's doing.