I would start with the basics and run the memtest and then the file system repair utility - if you are using NAS.

Memtest is done by rebooting the system and after POST hit the ESC or TAB key there you will see the basic menu - run the memtest for at least 45 min. If now errors then reboot and go to the Console screen and enter CTRL + ALT + X then run the File repair option.

Only do this if you are absolutely sure your RAID set is good!