T420 and CAD (DraftSight)

I bought a used T420 in excellent condition - seems to work fast and fine.

However when I loaded the free DraftSight 2D cad software I am having a problem.

The software loaded and my current drawing files will open however I cannot draw. I can input a command such as line and click in the field with the mouse but no line will be drawn. I cannot draw in a new drawing or and old existing one.

I can open an old file, delete an entity and undelete. But I cannot use any draw or dimension commands.

I have used Draftsight and prior to that other cad such as Autocad for many years on laptops and desktops older then this one and it has always worked fine.

Thanks very much for any help or ideas!

 

Update
I have got Draftsight to accept a command to draw a line, etc. buy changing the "Intel Graphics and Media Control Panel" settings to 60Hz and 16 bit color (from 32 bit and, for some reason, 50Hz)

However the curser in the drawing window moves in a jerky motion like the Snap Toggle is activated.

The cursor is also slow in other non cad applications. When CAD is not running the cursor in other applications is normal.

I think the problem is in the graphics / video portion of the PC

Anyone?

Help much appreciated!