I have Visual Studio set up to put me in XAML Mode, and use that almost exclusively. However, I'm finding that sometimes - usually just after I create a new element, put a blank line in it, and then save (but it doesn't appear to be consistent) it suddenly and jarringly switches me into Design mode.
I never noticed this happening in the release candidate.
Any ideas why this might be happening, and how I can stop it from happening?
I had a similar problem as you, when I set a new property it switched to Design view and hanged the entire Visual Studio.
Usually I take the following steps to find the issue:
Did you install a plugin/extension which caused this? If yes, then uninstall or disable it to see if it solves the problem.
Try starting it in safemode: See this MSDN post.
Start Visual Studio and log all activity: See how to do it here.
Repair Visual Studio.
In my case, the issue was related to a component (Intersoft to be exactly).