Drag-and-drop file does not work anymore

Question

Using Emacs 24.5 on a Gentoo/Kde workstation. Drag-and-drop of files used to work okay (as far as I remember), to open a new buffer on the dragged file.

Same behaviour when using emacs -Q.

It does not work anymore (FYI, I downgraded to emacs-23 (after reading Boregard's comment) and the drag-n-drop works perfectly.), or rather it sometimes works, but more often than not Emacs only displays "5 1" on the command line and adds "5 1" in the messages buffer.

This occurs for all users on the relevant computer. I guess it comes from some weird configuration on our side (otherwise other people would complain about this missing functionality). But how to pinpoint the source of this problem (and solve it, of course)?

Here is the output of M-x describe-variable x-dnd-types-alist requested by Nsukami _:

x-dnd-types-alist is a variable defined in `x-dnd.el'.
Value: (("text/uri-list" . x-dnd-handle-uri-list)
   ("text/x-moz-url" . x-dnd-handle-moz-url)
   ("_NETSCAPE_URL" . x-dnd-handle-uri-list)
   ("FILE_NAME" . x-dnd-handle-file-name)
   ("UTF8_STRING" . x-dnd-insert-utf8-text)
   ("text/plain;charset=UTF-8" . x-dnd-insert-utf8-text)
   ("text/plain;charset=utf-8" . x-dnd-insert-utf8-text)
   ("text/unicode" . x-dnd-insert-utf16-text)
   ("text/plain" . dnd-insert-text)
   ("COMPOUND_TEXT" . x-dnd-insert-ctext)
   ("STRING" . dnd-insert-text)
   ("TEXT" . dnd-insert-text))

EDIT: Sorry to be late in answering questions...

@Drew : same behaviour when using 'emacs -Q'

@Nsukami : here is the data

x-dnd-types-alist is a variable defined in `x-dnd.el'.
Value: (("text/uri-list" . x-dnd-handle-uri-list)
   ("text/x-moz-url" . x-dnd-handle-moz-url)
   ("_NETSCAPE_URL" . x-dnd-handle-uri-list)
   ("FILE_NAME" . x-dnd-handle-file-name)
   ("UTF8_STRING" . x-dnd-insert-utf8-text)
   ("text/plain;charset=UTF-8" . x-dnd-insert-utf8-text)
   ("text/plain;charset=utf-8" . x-dnd-insert-utf8-text)
   ("text/unicode" . x-dnd-insert-utf16-text)
   ("text/plain" . dnd-insert-text)
   ("COMPOUND_TEXT" . x-dnd-insert-ctext)
   ("STRING" . dnd-insert-text)
   ("TEXT" . dnd-insert-text))

FYI, I downgraded to emacs-23 (after reading Boregard's comment) and the drag-n-drop works perfectly.