Everyone will tell you this: re-download your cache, check your connections, re-load your client, I'm sure none of this will work
In my opinion it's your client it self, i'd suggest you to download the last version of client, if you already got the older one, If you already have the last version of client, then there's a problem with connections between the world 1 and your client, which only an high admin can help you with this.
Edited: Which client do you use the OpenGL client or the classic one?