To watch the logs as something is connected you can either monitor
gnome-system-monitor or other logging software, or use the command-line and enter
tail -f /var/log/kern.log
When your device is connected you will see a lot of information, such as
usb 1-3: new high-speed USB device number 5 using ehci_hcd
Initializing USB Mass Storage driver...
scsi2 : usb-storage 1-3:1.0
usbcore: registered new interface driver usb-storage
USB Mass Storage support registered.
usbcore: registered new interface driver uas
scsi 2:0:0:0: Direct-Access CREATIVE ZEN_Stone
You can keep the log open in the terminal and monitor when any errors occur as well. You can grep the log for past errors with
grep -i usb /var/log/kern.log, but you will probably need to use some more specific search terms with grep such as
error or the name of your hardware, as just using
usb as a search term will return a lot of results.
Most of the advice you read to restart the USB subsystem won't work in Ubuntu, and this way here at Ubuntu forums doesn't seem to work for me, but you could try restarting
udev by entering
sudo service udev restart
but you may very well still have to reboot.