'Error pasting data: interface not registered'

[Hilary]

This is the message I get when I try to drag and drop in an email from Outlook Express. Which is weird, as not that many months ago I could do this without problem. The process begins - you see a brief flash of the 'please wait' dialogue - and then I get the 'error pasting data: interface not registered' message.

Anyone have a fix for this?