Serial Number Disappeared

Today when I tried to find the serial number of my MacBook in "About This Mac" and System Profiler it says Serial Number System Sal#. I haven't replaced the logic board or had any service done and I'm wondering why it would suddenly disappear like this. My MacBook also has not been "sleeping" when the battery gets low, the computer just shuts off without the low power sleep state it usually goes into around ~1% battery left.

Any help is greatly appreciated.

Nope, I'll check that out when I get home!

Thanks.

Unfortunately neither of these resolved my Serial Number missing, as for the low power state I"m not sure yet.