Carrie/Justine/Rachel/everyone, you may or may not be aware of a pc virus that is doing the rounds. I am mentioning it here as my problem seems to have started when I received what I thought was a reply to an old email I sent to the Mumsnet team, with an attachment. I tried to click on the attachment to open it and it was blank. So if you get an odd email, which may appear to come from a friendly source, starting 'Re: XXXX' with an attachment, DO NOT open it, delete straight away. The virus then sends similar emails to everyone in your addressbook.
My DH has been attempting since yesterday night to sort this problem and we are still working on it.