Over the past few days I have noticed an annoying glitch with my highlight feature. Some times it will just stop in mid process and refuse to highlight the passage I want highlighted. Sometimes it will flip from the highlighted portion and highlight a different but contiguous section. Sometimes it will highlight but then immediately disappear when I release the mouse button. Sometimes it will only function if I start at the end of the section and move back toward the beginning of the part I want to highlight.
This is true regardless of whether I am using the function in word, or Adobe or online. No other problems with the computer that I have noted.

Anyone have any ideas why?