I'd run an equo deptest && equo libtest, then re-install kgrubeditor. kgrubeditor is designed to work in a kde4 environment, if you're mixing and matching between 3.5.10 and 4.2, then your issue it probably your $PATH - because kde is slotted, it can have two different versions of the same program installed at one time. It handles this by setting the executable path to include only kde3 stuff when you log into kde3, and only kde4 stuff when you log into kde4. When there's no duplication between 3.5 and 4, you can usually use the app in both environments. Kgrubeditor exists only for kde4, but some of its dependencies will exist for both - your problem could be because of this. Run the re-install, and if that doesn't seem to help then see if you can change your $PATH to include the kde4 stuff that you need to run kgrubeditor.