Often a USB device is not getting enough voltage to work properly when plugged into a computer (this is much more common with laptops) but then using an externally powered USB hub makes the device work.
Not at all, both straight lines at 0.5 microseconds timebase. Data- around 4V mark and Data+ slightly below, around 3.7V
So no wonder at the PC side nothing happens...
Can you unplug the PC and feed the 5V USB to the keyboard with a lab power supply? When you plug the 5V you should see some activities at the D+ and D- lines. If not it´s a HW issue not SW.
Also, maybe its me but the site you uploaded your dmesg log to says its empty.
You shouldn't upload the entire thing, just what happens when you unplug and replug in the device- it should be at the end.
Does the device enumerate itself- i.e. show up in any of the "device trees" shown on any of the three OS's you have plugged it into?
You can type "lsusb" on linux both before and after plugging it in, whatever changes.. Also, do any new entries show up in the /dev/ directory when you plug it in?
Also, there is a linux program you can install called usbview which can give you some additional information..
You could also install wireshark to see what is being sent back and forth from its perspective.