I have "JK Defrag Screen Saver" installed on my XP/Pro system as the primary screen saver. As a secondary screen saver, I just use the default Windows XP bouncing logo. I use the JK Defrag package bacause (1) it is free (2) it does something useful when I'm away from the computer (defrags it) and (3) as a defragger, it is friendly to RAID-1 disk systems (I have two such arrays on my computer). PROBLEM IS: it does not always engage after 15 minutes of inactivity. Any ideas?