i had that exact problem with the intellimouse. its nothing to do with the board, but its the mouse's usb port. i don't know what it is but i guess some of the older intellimouses have a ****ty connections in the port.
Athlon XP 1.58GHz | MSI KT3 Ultra2 | 256MB DDR PC-3000 | GeForce 4 ti4200 64mb @ 310/533 | IBM 120GXP 40.0GB | Det. 41.09 | DX 9 RC2 | Win XP SP1