IE9, richtext field producing unformatted frontend

[PuddingtonBeer]

Using IE9 I've been chasing my tail due to issues editing richtext fields. Upon editing an existing field's content, or adding a new item, I found that each time I saved an item and re-edited it, the content in TinyMCE was unformatted. After some time I discovered it didn't happen when using Firefox, which I had previously used to create some working examples.

I can only assume this issue will be reproducable. Perhaps someone else can verify my claim.