What is the common cause of an inaccurate system date and time?

An inaccurate system date and time is commonly due to a CMOS battery failure. The CMOS battery is responsible for powering the real-time clock (RTC) on the motherboard, which keeps track of the date and time even when the computer is turned off. When the CMOS battery is functioning properly, it maintains the correct time settings. However, if the battery starts to weaken or fails, the system loses this ability, often resulting in the date and time resetting to default values or becoming incorrect.

The other options may cause various symptoms in a computer system, but they do not directly affect the real-time clock. For instance, a faulty power supply could cause instability in the system or prevent it from turning on entirely, but it would not specifically lead to an inaccurate system date and time. Similarly, a corrupted user profile could lead to access or permissions issues, while overheating components may cause performance degradation or system shutdowns, but none of these issues would directly interfere with the system's ability to maintain the correct date and time settings. Therefore, the link between a failing CMOS battery and the inaccuracy of the system date and time is direct and well-established.