Keyboard Input Problem
My iMac has recently developed an intermittent fault when using the keyboard for typing. When it occurs it takes several seconds to put each character on the screen and options for the letter typed are offered (see screenshot below).
Typing beyond the letter in question and the system goes haywire with no response to what was actually typed and there is a background beeping as thought the system is trying to catchup, other keyboard commands such as backspace are also mis interpreted. I can't identify any particular trigger for the problem, a virus checker is showing no virus and a reboot corrects the problem.
Many thanks for any help.
iMac with Retina 5K display, Mac OS X (10.7.3)