I'm having the same issue with my brand new AsRock Z77E-ITX board.
I plugged the Flirc into the front ports on my box (which are wired to USB3 on board) and as with the previous posters, the device is recognised by windows (W7) and everything looks sweet, but the Flirc software doesn't detect that it's connected. So I disconnected and tried the rear ports (Also USB3) and I got it to detect once (but stupid me decided to keep playing around), and once I'd connected it back to the front ports and confirmed again it didn't work, when I plugged it back into the rear ports it failed to detect again there too!
I've since rebooted, tried all manor of combinations but the software will not connect, so I'm basically stuck. My board doesn't have any USB2 ports, so I don't have that option.