This can happen when you have certain OSnaps turned On and there are many possible snap points for AutoCAD to consider.
Try turning off the following OSnaps:
- Apparent Intersection
To turn off your OSnaps, right-click the OSNAP button on the status bar and select Settings. Then uncheck the selections you don't need and click Ok.
Then see if it happens again. If it does, then lets go into Options and go to the Selection tab to turn Off the Highlight options.
Now if it still happens, then it may be something more sinister and you may need to call us. The National Support Center can be reached at 800-808-7645.