Q: Why does my screen shake up and down?

My macbook computer screen shakes up and down so severely that it make me lose my place.  Sometimes it just suddenly drops the page I'm reading a few inches, as if someone were controlling it remotely and couldn't see what I was reading unless they lowered the screen...  This seems to only happen when I am on the internet, and my mouse icon sometimes disappears or goes a little haywire as well, as if someone else were controlling it.  When I try to repair the permissions on my HD, I repeatedly get the message:

Warning: SUID file "System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/MacOS/ARDAg ent" has been modified and will not be repaired.    

I also get other remote management error messages as well.

I am being stalked and would like to know if this means my computer is being routinely hacked into through remote management.  It seems like it is. 

Thanks!