This is so strange I don't know where to begin. I have two computers here at home, and one at work. When I view my blog on all three, it looks fine. There are two plugins I have tried to install: Subscribe Me, and Google Sitemap. After installation of either, the blog still looks fine on my main computer. However, on either of the other two systems, the right sidebar where all the links are suddenly drops to the bottom right of the screen, instead of the normal top right. When I uninstall the plugins and check again, the blog looks right again.
I thought maybe it was screen resolution. So, on my main system here, I installed the plugins and tested the blog on all resolutions from 800x600 up. No problems.
The other two computers I test with have 800x600. I cannot imagine what could be causing this but I have uninstalled these plugins until I figure it out.