I get this annoying one that
A. blocks the banner
B. opens down if you accidentally move your mouse over it, and therefore blocking a lot of important things (homepage, User CP, etc.)
C. is not closeable
D. renders the area under the banner somewhat unusable - even if unopened. I can't seem to click User CP or that sort of stuff even if the banner is still there.
This is what it looks like, opened. Note how it doesn't take up the usual banner space