Wait until you have started up and the disc drive light has slowed down or stopped Then run a Norton scan. Put the kettle on and have a brew and wait for Norton to complete.
You MUST NOT install more than one ANTI VIRUS program.
Ccleaner is quite safe and many forum members run it.(it is not a virus or spam/adware tool)
Spybot will slow your machine, but this is up to you.
Wait for advice re Norton from others. I do not use it.