USB 802.11n adapter fails to start after a reboot
An embedded-Linux user with a USB 802.11n adapter on a 2.6.35 kernel and a recent backport found that the adapter initialised on a cold start but failed after a reboot, logging that the target was unresponsive.
The log showed the USB device being found and its firmware download beginning before the failure.
Takeaway. On USB adapters, a failure only after a warm reboot can mean the device kept its state. Try a full power cycle, a different port or power source, and confirm the firmware files match the driver.