Default E-Mail settings appear OK but don't work.

[brush-head]

In addition to the MS Office suite, I also have on my machine Thunderbird,
Firefox and the latest version of OpenOffice 2.

I have the strange occurence detailed below. Everything is correct AFAIK.
It should work. If need be I can edit (safely inc backup) the registry, and
no I don't want to uninstall the Open Source apps or at least not for a good
while yet.

All OS and apps have up-to-date patches & everything else runs OK. I use
NOD32 for a/v etc and it does not interfere with anything AFAIK.

I have 1Gb RAM 2.4Ghz P4 & plenty (21+Gb) disk free.

All settings have been made in the Programs tab of IE6. That is currently
set like this:-

HTML Editor=Microsoft Office Front Page
E-mail=Microsoft Office Outlook
Newsgroups=Outlook Express
Internet Call=NetMeeting
Calendar=Microsoft Office Outlook
Contacts=Microsoft Office Outlook

Settings in Microsoft Office Outlook show that it is the default, for Mail,
Contacts & Calendar.

Thunderbird 1.5 is installed and was the default for Mail & News. It is no
longer set as the default in the application, and that has been double
checked.

Symptoms:
In IE6 taking the Read Mail option opens Outlook 2003 - OK
In IE6 taking the new Message option opens Thunderbird 1.5 - US
In IE6 taking the Send a link option opens Thunderbird 1.5 - US
In IE6 taking the Send a page option Opens Thunderbird 1.5 - US

In Firefox 1.05.01 taking the Read Mail option opens Thunderbird 1.5 - US
In Firefox 1.05.01 taking the New message option opens Outlook 2003 - OK
In Firefox 1.05.01 Send a Link option opens Outlook 2003 - OK
There is no option in Firefox to send a page.

Objective: to have Microsoft Outlook as the launching application in all
cases.

Many thanks for your help.