Microsoft updates on Outlook Express may have done it

Microsoft update their programs all the time
.
The outlook may have had its security settings enhanced in an update that stops file attachments with active scripts as an example. (usually they are trying to stop security holes hackers have found or exploited in their software)

Mike these updates occur behind the scenes and when you are connected to the internet.

I had a problem once with a windows 2000 peer to peer computer network because of a security update that users sharing a printer unless they each had a log in and password. This cost me about 3 hours to work out why my server suddenly stopped sharing out its printers to other computers.