This just happened to my site too! All I did was move the child-theme "shadow" to it's proper place in the structure at the same level as the main theme "options".
Checked with Dreamhost, and able to upload an "index.html" file with "test" in it, and it shows up at my site url. Dreamhost says that means the server is fine, but there is something wrong with the content.
I have a second website on the same server, and it is fine. Options theme author says it's not the theme, directed me to come here for support. Both ff and ie and someone with another computer get blank white page when going to my site. I can go using Filezilla and see all the directories there. Webftp from Dreamhost returns an error.
I'm not a newbie, but I've never experienced anything like this before. I checked and my wp-content directory has 755 file permissions. My second site that works fine has the same 755 file permissions.
Anybody have more ideas what to do with this?