Files should be safe. Will need to take drive out and connect to an external USB drive interface or connect in a desktop computer.
Do you know that the SD is functioning properly.
Your problem ''may'' be due to over heating caused by accumulated dust. If it starts again after a cooling down period then I would suggest unplugging, taking out battery and openning up and blowing out dust with some “canned air”.
If you get the problem fixed do the free upgrade to Winows 10.