I need a little help here, I have the 536 and has been working great. Last night we had a pretty bad thunderstorm and the power went out. When the power came back on several hours later, the screen on the 536 says to clear user data using sential software. I plugged it in to do so and the software isn't detecting the SD card. What do I need to do to fix this? I've had the 536 since January and haven't had any problems with it until now. Any help would be greatly appreciated.