My Laptop computer has become very slow. This is particularly noticeable when the screen refreshes. The icons take an age to change to the correct ones. PC Worlds (PC Performance) service has given up and suggests a re-installation of the OS (Windows XP Home) I am reluctant to do this except as a last resort. Have defragged and cleared out the usual junk - used RegVac run Virus and Spyware checks etc, but no improvement. Any suggestions????