Admin sub menus not showing up

Hi all I have just been adding a product in open t shirt and changed the open t shirt logo and the next thing i know is the
sub menus on my admin page have stopped working ie:

when I hover over catalog / attributes ( nothing shows) , open t shirts ( nothing shows )

I have tried all different browsers but still nothing?
Help!!!

Did you manage to fix this? It happened to me once and I can't remember if it needed fixing or just went away by itself.