An example file can be generated by doing the following:
touch `echo -e "testfile\xa0"`

Krusader fails to do anything with the file, including renaming, deleting and (for directories) entering; and instead claims it does not exist. I use UTF8 in both my locale and filesystems.

If the filenames are stored as QStrings, this might be the result of placeholders being substituted for invalid characters. If that's the case, this could also lead to accidental deletion of other files, if the placeholder characters are allowed in file names.
For a file manager, one should probably use the original string of bytes received from the filesystem when performing actions on a file.

The example file can be deleted from the shell via rm testfile<TAB>, or using midnight commander.

I get the same behaviour with Dolphin (1.7 from Debian testing), feel free to reassign the bug to the correct package.