Drag & Drop menu items problem

I am having problems with positioning some of my menu items (drag & drop). Some items I cannot move to a higher position in the hierarchy. No problem moving them down. These are all menu items I have added after populating a number of pages. I want to allocate these pages to new parent items. The temporary domain is http://http://af.habbe.uk/. The problem menu items are all under the parent item Reiseberichte. Deutschland 2013 (should be child of Reiseberichte 2013), April 2013 (should be child of Frankreich 2013), menut item Schweden 2013 (currently child of Schweden 2014) should be child of Reiseberichte.

I have deactivated all plug-ins. Didn’t help. I have tried Firefox. Didn’t help. I am using Chrome. I am no good with html or any coding. I hope someone can help. I suspect it has to do with the hierarchy that existed before I decided to change it.