Since upgrading to El Capitan on my iMac I get these few annoying issues every day! I have to restart the Mac to fix them, but then later on they may come back. So just wanted to highlight these in case others have the same because I cant see them reported online anywhere else, so dont know if its just me (maybe an app I have running?), or if its an El Capitan thing. It doesnt happen on my Macbook so maybe it is just my iMac. In which case I have no idea how to fix! 1) Dragging files stops working! Also dragging anything stops working! Can't drag icons around or off the dock. Cant drag emails into other folders. Cant drag attachments from mail onto Desktop. Cant drag files from FTP down to computer. 2) Copying and pasting stops working, but i think only in some applications. I THINK it may be just pasting because I can Cmd + X to cut some text, and can see its cut, but paste pastes nothing. Saying that, sometimes it pastes something old from the clipboard, so maybe copying is not working sometimes either. 3) Cant delete mail messages. Clicking the delete icon, hitting the delete key, or Moving to Trash does not work. Maybe related to number 1 above. I think all the above usually start happening at the same time, so probably related.