Bests & Worsts Reviews from Amazon

I ordered one of these and very carefully followed all instructions, including the instruction to "unlock" the scanner using the slider switch on the bottom of the scanner. When I had all the software loaded, I plugged in the scanner and tried to scan. The scanner seemed to make a small amount of progress, reversed itself, and then asked me to unlock the scanner and unplug/replug the USB cable. I slid the switch to lock and back to unlock, and unplugged and plugged the USB back in. No dice. I tried reverse psychology and locked the scanner. That didn't work either. I packaged it up and sent it back to Amazon, who rushed out a new scanner. Same problem. Returned it, too. I looked up this problem online and found that others have had this same problem, but most after a few months of light use. I suppose I got lucky in that both scanners failed immediately and within Amazon's return window.