Hey Per, I can't reproduce this issue on either a local site or the EPiServer demo site. Both pages are marked up with the X-UA-Compatible mode that they require, so should function correctly.
IE can be very sensitive about its browser and document modes and if you've set it specifically in the developer tools then it tends to ignore the X-UA-Compatible meta tag when loading the page. Check that this actually changes when you swap between admin mode and edit mode. Both modes should have IE10 as the browser mode; whereas document mode will be IE5 quirks for admin mode, and Standards for edit mode.
Let us know how it goes!
Hmm strange now I can't reproduce it but I got some windows update love when I started up my play box.
Happy it works :)
I'm running Windows 8 and IE 10 and I just noticed something strange.
When going into admin mode I need to change to document mode quirks to make it display correctly (independent of browser mode 8,9,10). Switching back to edit mode without changeing the document mode back to standard will cause a blank screen.