My desktop computer behaved differently: it refused to boot normally; restarted often before its starting up. Then, in a day it refused to open up with the following display on its monitor before its opening up:
The firmware has detected that a CMOS battery failure occurred.
Press the Enter key to continue.
On Googling with the above sentence and the word, CMOS, I found out that there will be also an error in date and time display due to low voltage from CMOS battery. And that that CMOS battery has to be replaced with a new one to restore the computer to its normal functioning. I found the date and time malfunctioning as said! I adjusted it to the correct displaying. But the malfunctioning continued! The next day, the computer refused to start showing that same display on the screen. I rushed to the stores and bought this large-sized button cell, the so called CMOS battery and replaced the old one with it. And now hurray! The computer booted and started up. I adjusted the clock to the correct date and time. There was no malfunctioning of the clock too!