I have the exact same issue! As long as I stay in the comment bubble, it will automatically jump to draft view!
even during I am typing, sometime the typing position will jump randomly to elsewhere as if someone pressed the "home" button or something. I has long suspected it is my computer hardware problem, until I realize it may be the Office issue. I happen when
I was in windows 7 and in now windows 8.
I had the problem when I was using Office 2010 Volume Label edition. Then I removed the office and installed the Retail Edition Trial. It doesn't have the issue of draft view jumping in Retail Edition.
I wonder if it could be a possible that the issue is Volume-Label specific problem.