Problem with IE and CSS

Hi there!

I have a big problem with my css stylesheet and IE. This is my first Theme so it would be very great if you could help me.

You can see my site on http://www.rosewick.com/index.php – In Firefox everything is going fine – but with IE there are still some style-problems.

E.g.:
Sometimes the header backgrounds will not loaded, sometimes they do but if you then mark all the backgrounds hide.

Have you ever heard about that problem?

Bye rws