I think I've fixed some of the issues I've had on my machine with USB and certain devices. It appears the EHCI driver under Linux kernels 2.4 isn't all that stable, so I reverted all of my devices to use the usb-ohci driver instead. Amazingly, it seems all of the devices I've had trouble with before (the M-Audio Keystation, primarily) seem to work just fine now. Fancy that.