Just to add my experience....I have a wi-fi only nook with serial version 1002xxxx and was able to soft root without any problems. My nook was also running firmware version 1.40 (not 1.41). I *think* the firmware version may have more to do with not being able to soft root than the serial #. My suggestion would be to avoid softrooting if you have a nook with a serial # of 1003xxxxx OR firmware version 1.41.
dordale
