Your blog looks fine to me so I would be looking at your own PC and more specifically the browser.
What are you using at the moment, IE/Firefox/Opera etc and what version.
I would suggest that you check the settings within the browser, clear coockies and cache etc and if you can try looking at your blog with a different browser on the same machine. Eg if you’re using IE and it looks funny, install Firefox if you can and look at your blog through that.
Actually, I would install Firefox 2 if you haven’t already done so.