Bug spalt when moving or copying vertex/lines

Hello guys!

Thanks very much for this great place

I have been having this bug spat for a while, SU 2014 and SU 2015.
Looks like when I’m copyng with
ctrl + move or just moving vertex/lines around, get this bug splat. Not alway and tent to be after repetitions of theses operations ( ctrl + m or just moving and always with vertex or lines) and have happened with diferents files so I presume is not a file issue. Any guidance on how to tackle this will be great.

Thanks in advance!
bug splat