I tried right clicking it, which gave me the options of move or hide. I hid that sucker. Re started Revit and it's back.
System clean? I have up to date anti virus and run a full scan daily.
I use 32 bit. With trusty old XP.
I import dwg files, but hey, Revit wouldn't have that on the tool bar if it wasn't ok now would they? The artifact is there anyway even when there is no project open. I haven't had AutoCAD for some years so can't "clean" dwg files that other consultants send me readily.