Two thoughts in case unexplicable stuff happens again:
SMART doesn’t detect all possible errors, especially not on SSDs. (It was originally designed as an early-warning system for mechanical failures on spinning rust drives, and later somewhat expanded.)
A faulty RAM chip can cause all sorts of subtle (and not-so-subtle) mayhem but is often overlooked as a possible cause for disk troubles. If in doubt, MemTest86 is your friend!
Two thoughts in case unexplicable stuff happens again:
I even ran MemTest86 and it showed things to be all fine. I recently bought new memory (2 GB) for the netbook.