If you have installed the Windows 98 drivers from CD-rom by accident, they will conflict with the 2k / XP drivers.
1..Restart your computer.
2..Just before it loads 2k / XP, start pressing F8 until the boot menu comes up.
3..Select safe mode.
4..Right-click My Computer, go to Properties, Hardware, Device Manager.
5..Double-click Sound, Video, and Game controllers.
6..Look for any MOTU MIDI drivers, and right-click and remove them.
7..Reboot and load the correct drivers.