I switched my computer on and the following message came up so I selected Outlook express.

"An important choice to make:"

Your browser is an important piece of software on your computer. It is what you use to surf the internet: it’s the window around the web sites you visit.
There are many browsers available, each with a variety of features. On the next screen, you can select and install any additional browser(s) you want.
Please Note: The Browser Choice update unpinned your browser, Microsoft Windows Internet Explorer, from your taskbar, but you can pin it back if you want. Click here to learn more.
Internet Explorer is still available from the Start/All Programs menu.
Before proceeding, please confirm that you are connected to the internet.

OK

The next thing that happend my outlook express opened and it downloaded over 1,000 old messages losing my exsting Outlook Express setup.
I rememberd how to find the old setup and all was well but when I opened my outlook express this morning the same thing happend again. A load of old messages downloaded and my old Outlook Express set up with all the files disapeared.
HELP.

It's possible that Outlook Express didn't finish downloading all emails due to interrupted Internet connection, huge email attachments, etc, the next time you open it, it tried to start over. If your email account has a web version, logged on to it and delete the emails on the server directly.

BTW, MS has stopped the development of Outlook Express, you may want to check out Windows Live Mail.