Time is altered upon startup.

Bryan I am assuming you have checked the Date and Time & Region and Language settings in the Control Panel?? If not do so and then if they are set ok then run these
SFC /SCANNOW Command - System File Checker
Disk Check < if necessary include the /f and /r in the command line as per Option2 run these in safe mode and the sfc often best run for two to three runs

if no fix then these

SUPERAntiSpyware | Remove Malware | Remove Spyware - AntiMalware, AntiSpyware, AntiAdware!
Malwarebytes | Malwarebytes Anti-Malware Premium
AdwCleaner Download
ADW download from bleeping computer delete any rubbish found with the malware scans

Bryan have you been or are you using any Linux systems?
Some Linux operating systems will change the time in the bios.

Bryan have you been or are you using any Linux systems?
Some Linux operating systems will change the time in the bios.

I tried running Kali Linux Live USB but it doesn't alter the time. It's the only Linux based operating system that I used. And I think I last used it 3 months ago. I don't have any other Linux OS. BUT, I have MSYS in my computer. I also have Cygwin but I uninstalled it. These 2 programs doesn't change my system time in the past. I also had an MSYS2 in my PC but I also uninstalled it (I think this caused the problem but I'm still not sure about it).

Bryan I am assuming you have checked the Date and Time & Region and Language settings in the Control Panel??

Yes I do. My system clock is synchronized to a network time: "ntp.pagasa.dost.gov.ph", the Philippine Standard Time. The clock is always synchronized on a scheduled basis. If I clicked the "Update Now" button on Internet Time Settings, this will synchronize my time to the accurate time on my country. The next synchronization will be based to whatever time I updated it. So when I update it too early and boot the PC tomorrow late, I think it will not synchronize the time.

If not do so and then if they are set ok then run these
SFC /SCANNOW Command - System File Checker
Disk Check < if necessary include the /f and /r in the command line as per Option2 run these in safe mode and the sfc often best run for two to three runs

if no fix then these

SUPERAntiSpyware | Remove Malware | Remove Spyware - AntiMalware, AntiSpyware, AntiAdware!
Malwarebytes | Malwarebytes Anti-Malware Premium
AdwCleaner Download
ADW download from bleeping computer delete any rubbish found with the malware scans

I will try these options.

I also suspect that maybe my CMOS battery is failing? Can this be a reason to my faulty system time?

Thanks!

~Bryan~