USB Drive isn't recognized; new USB devices not showing up

I've been having some issues getting my USB devices to work properly with Knoppix. My biggest issue is that my flash drives aren't detected at all. Specifically, Knoppix doesn't seem to detect that it's even plugged into the computer; if I boot up Knoppix with the flash drive plugged in, the indicator light stays green, but if I unplug it then plug it back in the indicator light is dead.

Also, if I unplug something like my USB keyboard and then plug it back in, it no longer works and I have to reboot. My flash drives and USB devices all work fine in Windows XP and Ubuntu, whether I add them or have them connected while booting.

Anybody know what's going on?