No i can't, because there is no snippet there to demonstrate;
the problem doesn't occur on save/postback, it occurs when i insert a snippet via the codes toolbar!
so, if u insert an snippet called IsThisBuggy with Text "<div><!--banner starts--><em>Hello World</em><!--banner ends--></div>" right below "E-Mail signature" then u should be able to reproduce this behaviour! When inserting this snippet, "<!--banner starts--> gets deleted!