That is not normal and is a very common problem caused by 1 or both of these very common problems below. The links below explain the cause of the problem and provide the solution.
cPanel HotLink Protection Tool Problem
http://forum.ait-pro.com/forums/topic/read-me-first-pro/#cpanel-hotlink-protection
WordPress flush_rewrite_rules function problem
http://forum.ait-pro.com/forums/topic/read-me-first-pro/#flush-rewrite-rules