I am logged in yet can't post another reply to my thread

When I try to go to one of my threads, for some reason I am not logged in ( yet on any other post I created I am logged in...) Is there any reason for this..?
My post is Windows Start Button Not Working Right
on my two other posts I am logged in,but for some reason when I try to reply on that one, I am logged out ( and will not let me log in to reply...)
Any help would be appriciated...
Thankyou!
EDIT: actually it is when I go to just the 'customization' page that this happens, but I still have this problem with my post...

I am not sure, I was using a school computer =P I am on my home computer now, and everything works fine.
Thankyou! If I run into this problem again, I will do what you told me to do above =P and if that doesn't work...I will mention the problem again...(hopefully not)