Comment 3 for bug 203592

I also have the same problem in Hardy. Here's a step-by-step:

* Run 'systemsettings'.
* Select 'Default Applications'.
* In the list on the left side, select 'File Associations'.
* In the 'Find filename pattern:' text entry, type the file extension, in my case, 'pdf'.
* The list is filtered to just one entry: Application->pdf.
* Select that entry, and change the order of applications on the right side.
* Click Apply.
* The Updating settings dialog appears, then disappears.
* Both konqueror and dolphin still open PDFs using the wrong application.

Interestingly, I also removed an application from the list of valid PDF viewers - KGhostView. That change stuck, but not the reordering.