I just recently tried the keyboard on a Sony Vaio VPCSE27FX/B laptop which also has the Z68 chipset. I get the same exact behavior as I do with my Asus/Gigabyte motherboards. So it's definitely seem like a Z68 chipset USB driver bug. I have a couple more laptops in the house that don't use the Z68 chipset. I'll try the keyboard out and see if the behavior is similar or not.
I did have a chat with an Intel Support Engineer. He claims that the Z68 USB chipset driver is bug free.
Here's his response:
Michael: thank you for holding
Michael: we have no bug with Intel 6 Series/C200 Series Chipset Family USB Controller, but you might have a defective chipset, but you have to troubleshoot to determine that
Michael: I recommend you escalate your issue with your system manufacturer, so they can try to duplicate the problem
Michael: we have no problems with our 6 series chipsets and USB.
Michael: There was a problem before about our 6 series but it was the SATA ports, not USB.
: I'm referring to the software driver. So you're saying that your usb chipset is bug free?
: I'm skeptical of that claim because I'm a software developer myself
Michael: correct, the USB chipset is bug free, we have tested our drivers, and we know they work good. There is have to be something else causing the issue
Michael: anything else for today?
Really, it's bug free? Yeah, right.