This is why power buttons on keyboards is a bad design idea!
Invalidation usually isn't anything serious - just leave the system alone for a while and it will usually resolve itself. It happens if there's disk activity during a crash, reboot, or power cycle.* I've never lost data from an invalidated partition (except maybe the destination file being written to during the crash).
When you start getting "Checksum error on block
", that is when you need to start thinking about reformatting. But those errors are rarely related to validation and usually indicate some other problem.
* And I suspect this is why the Suspend/Reboot requesters always tell you to wait for disk activity to finish
