Hi,

I have tried in Kubuntu Dapper to set some default applications for various file extensions. I've done this from Konqueror. For some reason Kubuntu does remember my settings, but does not use them. E.g. I told kubuntu to play mpg files with mplayer. When I look up the settings for that, they seem fine. But when I click on a mpg file, it opens with Kaffeine.
The same thing goes for my default browser (firefox) and mail program (thunderbird). I have these defaults through the system settings thingy. They both get registered ok, but it doesn't work.
Does anyone know how to correct this?

Have you tried using Open With > Other > Remember application association for this type of file?

Also, you might want to make sure you own the KDE settings directory:

I tried both of those, but unfortunately it didn't work.

If you create a new user, do that new user's settings stick?

I have just tested this. When I create a new user everything works as it should. So what's the difference between the account I created when I installed Kubuntu and the one I added a few moments ago?

I don't know. Something happened to your settings in ~/.kde, I would guess.

It gets a little more complicated now. I did some additional tests:
I created to links on my desktop. One with an internet address, the other with a mailto: adress. When I click the internet address it opens in Firefox, which is good. When I click the mailto link it opens a new message in Thunderbird, which is also good.
But when I click on an url in an email message in Thunderbird, the page opens in Konqueror, which it shouldn't do. Also when I try to open my hotmail inbox from Kopete, it's also opened in Konqueror.
I really don't get it......

try the command
and choose firefox

Well, it helped a little. Links from thunderbird are now opening in Firefox. But Kopete still tries to open hotmail in Konqueror. Could it be that that is hardcoded in Kopete?

I was looking to solve the same problem in that Kopete would try to open Hotmail in Konqueror. I found the solution thanks to thanks to XstatyK over in the Kubuntu Forum.

Do the following:

In KDE control center, go to File Browsing, File Associations. Under known types choose text, then choose html. In the Application Preference Order move the browser you want to the top of the list.

It worked for me!!
Wild Willy

Thank you very much! That did the trick.