I have the same thing happen, but only when I start a new thread or type these replies, and I also can't cut and paste so I can't type in Word and copy it to here. I have a new computer and keyboard.

I just took Tessagin's advice and went into my settings and changed my keyboard layout (Message Editor Interface)from Enhanced to Standard and everything works now. I also tried Basic which also works but without some editing features. Thanks Tessagin, this issue has plagued me for weeks.

Changing the battery in a wireless keyboard also helps. I change the battery in the mouse at the same time.