An "Unexpected Reboot" refers to a situation where a computer or electronic device restarts without any prior warning or user intervention. This can occur due to various reasons, including software crashes, hardware failures, or power outages. Such reboots can lead to data loss or corruption, especially if unsaved work is present. To troubleshoot an unexpected reboot, users should check for error messages, review system logs, and ensure that all software and drivers are up to date. Additionally, hardware components like the power supply or RAM may need inspection to prevent future occurrences.