While trying to get USB support for USB serial devices working on my NS-K330 running FreeBSD 9-CURRENT, I discovered that the current patched kernel only reliably supports USB 2.0 devices. Specifically, the USB ports on the NS-K330 seem to only cope with USB 2.0 devices being inserted and removed. Inserting a USB 1.1 device seems to jam up the port from that point onwards — not only is the 1.1 device not even recognised (there’s no ugen device created, let alone any sign from the kernel’s OHCI drive that it has seen the device insertion) but the port then becomes useless for subsequent USB 2.0 device insertions.
Of course, this only applies to FreeBSD 9-CURRENT as patched around March 2011. If you’re reading this many months or years later, the problem may have been solved.