How to disconnect "undefined" device?

[Markus Fischer]

I got my Neo 1973 today and let me tell you first: It looks awesome! Even 
better than on the pictures...

Unfortunately I need some help by flashing the Kernel and the Root-Filesystem. 

I did Download
wget chooseopen.com/openmoko/build/dfu-util
chooseopen.com/openmoko/build/openmoko-devel-image-fic-gta01-20070803091138.rootfs.jffs2 
chooseopen.com/openmoko/build/uImage-2.6.21.6-moko10-r1_0_0_2388_0-fic-gta01.bin
$ chmod +x dfu-util

press Aux-Button and Power-Button on Neo
connect via USB-Cable to PC (Fedora 5)
Set console to usb

su => Root-Password
# ./dfu-util -a 3 -R -D uImage-2.6.21.6-moko10-r1_0_0_2388_0-fic-gta01.bin

I got something like

Opening USB Device 0x0000:0x0000...
Claiming USB DFU Runtime Interface...
Determining device status: state = appIDLE, status = 0
Device really in Runtime Mode, send DFU detach request...
Resetting USB...
Opening USB Device...
Found Runtime: [0x413c:0x8106] devnum=4, cfg=0, intf=0, alt=3, 
name="UNDEFINED"
Claiming USB DFU Interface...
Setting Alternate Setting ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
Error obtaining DFU functional descriptor: error sending control message: 
Broken pipe

Probably the Neo got a timeout, while I was preparing to flash and powered 
itself down...

So I put it on again with Aux and Power-Button
# ./dfu-util -a 3 -R -D uImage-2.6.21.6-moko10-r1_0_0_2388_0-fic-gta01.bin

resulting in: More than one DFU capable USB device found, you might try 
`--list' and then disconnect all but one device

# ./dfu-util -l
Found Runtime: [0x1457:0x5119] devnum=15, cfg=0, intf=2, alt=0, name="USB 
Device Firmware Upgrade"
Found Runtime: [0x413c:0x8106] devnum=4, cfg=0, intf=0, alt=0, 
name="UNDEFINED"

How can I disconnect the "undefined" device, so I can successfully flash the 
Neo?

Thanks for advice!

Markus