Mouse Trouble
For no reason I could see, my computer suddenly developed cursor/mouse trouble.
Typing text did not show up immediately, but suffered a delayed action before it showed.
Highlighting by holding the mouse L/H key down did not work.
Using the page slider was jumpy as was the mouse scroll - instead of scrolling it had delayed jumps.
Even selecting items with the cursor did not work.
This all happened on the Internet, whatever browser I used, but offline Skype worked perfectly, as normal.
My PC was almost unusable.
The web said if restarting and/or shutdown did not cure it, to try a different USB port with the mouse plug.
I unplugged my keyboard and mouse from the PC USB sockets and swapped them round, then restarted.
BINGO !!! It worked, my mouse is now doing everything perfect again and all is back to normal.