Zero Length Lines

It seems out of nowhere this problem popped up. When I'm working in strictly 2D, I'll point at say 90 degrees (with tracking) and type in .5 and it will say:

"Specify next point or [undo]: .5

Zero length line created at (19'-6 7/8", 1'-2 5/8", 0'-0")"

The odd thing is if I exit the command, move anywhere else, repeat the same input and it works.

What causes the zero length line? Anyway I can outright avoid it?

Maybe it's an Osnap thing. If your osnaps are on, replicate the zero length line; then turn osnaps off and try it again.

It is definitely related to O-snaps, I've tried to single one out but at times it seems they can all be to blame dependent on the situation.

The thing that bothers me is it will snap to places (only when I'm near objects) without displaying any icon that it has selected said place.

Basically I'll point into nothingness enter a value and the line will snap to the closest mid-point,end-point, etc. without letting me know it has selected that point.

I haven't recently edited any options pertaining to o-snaps, other than turning a few on/off to see if it was them in particular.

Anyone know how I can make it so the selection-pick-boxes of O-snap are always displayed when it has them selected?

From AutoDesk:

Zero Length Line Created

Solution

This error can occur when you are using OSNAPs and AutoCAD® snaps to the start point, instead of the next point indicated. You can resolve this error with one of the following suggestions:

• Turn off OSNAPS temporarily.
  
• In the Options dialog box, on the User Preferences tab, set the Priority for Coordinate Data Entry to Keyboard entry (instead of Running object snap).