Can you help me with a Windows 10 copy/paste issue that recently developed?

I'm unable to use my mouse for copy/paste by left clicking on the mouse and dragging across the text I want to copy. The blue area I create now tends to break up or sometimes highlight areas I don't intend to copy. So I can't get the area I want copied continuously blue. The only way I can do this is to left click on the bottom right side end of the desired area and then while holding the "shift" down while clicking of the upper left of the area I want to copy. Also I now notice that in my browser when I want to use the arrow key to go to a previous page that I can no longer left click and hold the arrow key to look at the drop down menu to decide which page to go to. Instead it will race rapidly through the whole sequence in the drop down menu. So now to get to where I want to go I have to back click individually at a time to work my way to where I want to be. I rather suspect these two issues are tied together because the problems arose simultaneously. I tried to restore the computer to an earlier time but there was one item that failed to restore properly thereby causing the restore process to abort. I have a currently active anti-virus on my computer so I don't see the problem being a Trojan or a virus. What do I do now?