To add and clerify - the error in editing is the same in FF and IE and from all commputers. I am sure that something must be wring with MY DNN application.
I hope I get you right - no red crossed icon is displayed but I found this:
Warning: reference to undefined property dnn.controls.length
Source file: http://www.server.com/js/dnn.controls.dnntree.js
Row: 614
and Row 623
Warning: reference to undefined property me._m_oMenu.name
Source file: http://www.server.com /controls/SolpartMenu/spmenu.js
Row: 1567
Warning: reference to undefined property this._m_oTblMenuBar
Source file: http://www.server.com /controls/SolpartMenu/spmenu.js
Row: 116
Warning: reference to undefined property this._m_oMenuMove
Source file: http://www.server.com/12dz/controls/SolpartMenu/spmenu.js
Row: 114
Warning: reference to undefined property this._m_oDOM
Source file: http://www.server.com/12dz/controls/SolpartMenu/spmenu.js
Row: 112
Warning: reference to undefined property spm_getTags("BODY")[0].onclick
Source file: http://www.server.com/controls/SolpartMenu/spmenu.js
Row: 267