Screen going weird when replying

Hello.This problem recently occured.
When I open the reply window, it goes weird. The Home, Help, etc. buttons are stacked, I only can see half the textbox as normal, and the page is extended at the sides.Does anybody know what is happening?Browser: IE8 (planning to switch to Firefox though)

probably IE not rendering the css properly.

When going into compatibility mode the textbox it correct but then the other problems remain...Yeah could be but everything was normal before on the same IE installation...