Well, this is a bit sad, but I guess it's still a beta.
I was just entering some code sample in a blog entry via Windows Live Writer when it removed the line breaks from all my preformatted code sections (ie the <pre> sections).
Here's some screen shots of the bug in action:
1. Entering the <pre> code:
2. Switching back to Web view (F11)
3. Switching back to HTML view (Shift+F11). Nothing else was pressed. You can see the <pre /> section is now messed up.
4. And back to Web view just to make sure it's been butchered (F11 again)
A quick look on google doesn't show anything about it. Guess I'll go submit a bug report.