UMSD is used by some Memory sticks that you shove in the USB port. On XP the stick should be recognised and useable without it, but some functions such as making it a bootable stick will not be accessible, neither will you be able to set a password protected area If you just use memory sticks as memory, try removing UMSD and if mem stick still works, leave it as is. UMSD places an icon in systray which has a green and white horizontal bar at the bottom.