Windows PC Randomly Restarts Even at the Login Screen—What Should I Check?

The behavior could be caused by damaged Windows files or a failing SSD. Back up important personal files as soon as possible, then check the drive's health and consider reinstalling Windows if the hardware passes testing. A reinstall will not fix an SSD that is beginning to fail, so test the drive first if possible.

Open SrtTrail.txt from the recovery environment and read the repair details. It may identify a specific driver, boot file, or disk-related problem, although the log is not always conclusive. Also run the available disk and system-file checks from recovery rather than relying only on Startup Repair.

Check Event Viewer for errors immediately before each restart. Look under Windows Logs for System events, especially unexpected shutdowns, hardware errors, driver failures, or storage warnings. The exact event details may help distinguish a software crash from a power or hardware problem.

The keyboard lights switching off and on suggests the whole machine is restarting rather than merely logging Windows out. That makes a power, motherboard, memory, overheating, or other hardware fault worth investigating. Run memory and hardware diagnostics, disconnect unnecessary peripherals, and test with stable power before focusing only on malware.

Since Safe Mode also restarts, a normal startup program is less likely to be the cause. Hardware, overheating, power delivery, storage failure, or low-level drivers become more likely. Check CPU temperatures and cooling, make sure the fans are working, and inspect that the CPU cooler is mounted correctly.