I’m starting to see a theme here

I hit this one after installing the Simpla theme, but you could hit this with any theme. Symptoms (after switching to a new Wordpress theme):

• The screenshot for the theme doesnt show up in the theme selector
• The pages on the blog are unstyled
• Theme images don’t load correctly
• Trying to manually open the URL’s for the stylesheets, images, etc, gives you a 404 page

The problem was that permissions were not set correctly on the unzipped theme folder. I had to make sure there was read and execute access granted on the folder and all the theme files (chmod 755 for you command-line junkies). You could probably do this through your FTP client, if it’s a decent one (I recommend Smart FTP).