3 weeks ago i bought a 4GB U3 SanDisk Cruzer Micro. It has worked fine up until now. I plugged it in today, and nothing happened. No amber on light, it just sat there. The USB port is fine, and I have tried it on several other machines with the same result. It was working fine earlier today, not 4 or 5 hours ago. Any thoughts? This drive is very important to me.