Default browser

My default browser is now Opera and is shown as such. I have been using FF, but even though I've set Opera as default if I click an Internet link say in Outlook, it takes me back to FF. The same when I connect to the internet, (I use a dongle) it still opens FF.
I've got default browser for XP and again that shows Opera as the default.
I've had a similar problem before and I thought I had made a post about it, but I can't find it using the search facility in BBS.
Thanks

 

Thanks Pete, I've found that post but it doesn't help. I've done everything I can to set Opera as the default as such, but still I keep geting put back to FF.