Can not copy and paste all the time

I called dell support and they seemed to fix the problem but i had to start up with a selective start up and little to nothing running. I didnt like that so i changed it back and now my copy and paste is back to not working all the time. They downloaded a driver im not  sure which one though during our session. Does anybody know what i can do to get the copy and paste working all the time without a selective start up?