If your computer system is crashing frequently then you can run First Aid (Disk Utility) for checking and repairing file system errors. It will check for defects and ,in many cases repair them. This could be external hard drive.
1. Open Disk Utility and press cmd+space.
2. Select Disk Utility option.
3. Select the volume you wish to run First Aid on.
It will check for defects and, in many cases, repair them. This could be an external hard drive.