Ok, I played with Marv's account and this is what I found.
1) his entire account ran very slowly
2) his PM has quiet a few messages in it. I had not realized how much people use this funtion
3) he had never "cleared" message. From the main page, down at the bottom, is "Mark all messages as read". I did this for him
4) The entire board started to display much faster immediately
5) I had not problem sending and replying to PMs
Try this, and if it doesn't make a difference, I'll arrange to "take over" your account and see what I can see.