Hi
I must admit I certainly haven't encountered this before. If it had happened to me my only solution would be a repair install of Xtreme or possibly a system resore to a point before the problem occured.
Have you tried right clicking on them and altering their position in the properties box? This would at least tell you they can be moved albeit not dragged.
Certainly if they are visible and editable they should be dragable, not much help, sorry.
Derek