My friend has a budget computer with i3 CPU and 4GB RAM. His computer always gets the same problem of Windows not booting up. For like 1 year we tried to reinstall Windows several times and after doing some fixes or taking the PC to repair shop, his computer will run fine for 2-3 months and then will develop the same boot problem. After powering ON the PC, BIOS screen will show and Windows logo will appear but then an error message will come saying something like "Windows is not able to start, ETC and vice versa". Sometimes Windows tries to repair itself with Startup Repair but then it fails. We have tried different Windows versions from Windows 7 to Windows 10 but this booting problem comes every time. We also replaced the HDD but the problem continues.
What could be the CULPRIT?