That's probably just a list of "recently" accessed stationery, like Word's Recent Documents. They will probably go away after you select other stationery items a few more times.
Try right-clicking Desktop Taskbar, Properties, Advanced. See if there's an option for removing records of recently accessed documents, programs and websites. Choose that and see whether it affects OE (probably not). If not, it's not a big deal.
If you're really keen, there's a registry entry which relates to the recent stationery items. You can delete the old entries from there. Post back if you really want to do it.