Are the keys on your keyboard sticking or is that ccccrrrrreeeeeaaaaaattttttiiiiiivvvvvvvveeeeeee writing?
Go into SETTINGS, CONTROL PANEL, KEYBOARD and check your settings.
Malfunctioning software related to the keyboard. Now seems OK
About to do what you suggested w Logitech help sheet. Now problem back.
system scanned clean of junk etc.
tHX