This is in reference to the vertical line that you 
can relocate to any bar by simply left-clicking your mouse while the curser is located over the desired new location of the 
vertical line. 
 
My earlier post stated that I can no longer relocate 
the placement of the vertical line with a single left mouse click.
 
Since that earlier post, I have discovered that I 
can double-click to make a vertical line that is associated with a BLACK 
FLAG which marks the beginning of a range. 
 
I can then  double click on another bar, and another 
vertical line will appear with an opposite facing BLACK FLAG.
 
This feature of AB obviously allows one to identify a 
range of bars under consideration.
 
I can STILL relocate the vertical line with a single 
click in the copy of AB that is installed on my BACKUP computer, but my 
main computer still will not do this. 
 
This problem suddenly appeared in my main computer 
today.  All suggestions to fix this are appreciated. Ron 
D