|If you do a restore routine - first copy all your personal files (the stuff you wouldn't wish to lose) to external storage. Typically dvd, but an external hard drive too if possible. Check the copies are ok as well before proceeding with any restore/rebuild routines.|
If the system was to go back to wherever under warranty repairs/replacement etc., again safeguard your file as above - first.
Factory resets/restores will erase all your personal files in the process. Which is why the above safeguard routine.