I see it's hard to get a complete log from dmesg. Sorry my fault.

Please
install sysklogd, [ apt-get install sysklogd ]
reboot,
check if you got a proper /var/log/syslog file [ tail /var/log/syslog ]
start h-e-n,
if you bother, insert a note about the fact to syslog [ logger '###########h-e-n gui started#######' ]
plug in your problematic device,
click speed, vbus in h-e-n GUI
if you bother, insert a note about the fact to syslog [ logger '###########h-e-n vbus clicked#######' ]
wait 15 seconds
click enumerate in h-e-n GUI
wait another 15 sec
close h-e-n
send the file here [ cp /var/log/syslog someplace/h-e-n_syslog.txt; attach someplace/h-e-n_syslog.txt to a post here ]

don't forget to reset the syslog file every now and then ( once a week? [ echo >/var/log/syslog ]), or uninstall sysklogd pkg eventually. If you don't either, your rootfs will fill up eventually, that's not a good thing long term.

Thanks again for helping with this, and sorry for my lack to notice what's the problem with those logs.

cheers
jOERG