KDVI doesn't have PageUp configured.

Sorry, I forgot: This is Kubunutu Dapper Flight 5, KDVI version 4:3.5.2-0ubuntu2.

Unable to reproduce with the latest Dapper packages (4:3.5.2-0ubuntu5).
Can you retry with Flight 7 and/or provide more information.

Upgrading to 4:3.5.2-0ubuntu5 has not solved the problem. "Previous Page" remains unconfigured. What other information do you want me to provide?

In the course I found another strange behaviour: In the "Configure Shortcuts" dialog, hitting the "Defaults" button removes the Ctrl+G shortcut for "Go to Page..." (along with PageUp) in spite of the fact that this was part of the original configuration.

After a quick look at the KDVI package it seems shortcuts are absolutely not defined in each package: this is something orthogonal to all applications.

So can you have a look into KDE Control Center, Regional & accessibility, Keyboard shortcuts. The 3rd tab (application shortcuts) is where all default shortcuts for KDE are defined. Here you should have PgUp and PgDn defined. You can try to change your scheme.

As a last resort, could you try to create a new user and check whether the problem remains.

@Michel: Yes, that has solved the problem. Thanks a lot!