There are many reasons why an operating system may become unstable. There are several ways to fix the most common faults.
Necessary
Windows installation disc
Instructions
Step 1
Try using System Restore first. If your OS boots but is unstable, open Control Panel and go to the System and Security menu. Find the item "Back up and restore" and go to the sub-item "Restore system settings or computer".
Step 2
Click the Start System Restore button. Wait while the OS collects information about existing restore points. Activate the item "Choose another restore point" and click the "Next" button. Select the earliest restore point based on the creation date. Click the Search for Affected Programs button. See which programs will be removed after performing a system restore. Click the "Next" button and confirm the start of the recovery process.
Step 3
After a while, the computer will reboot, and the system recovery process will continue after the OS boots. If you cannot log in, then press the F8 key 5-10 seconds after turning on the computer. Select Run Last Known Good Configuration. This sometimes allows Windows to start to perform a system restore.
Step 4
If the above method did not work, then try selecting "Windows Safe Mode". In the new window, select the "Safe Mode with Driver Support" option. Wait for the operating system to start in the selected mode. Try starting the Windows recovery process as described above.
Step 5
Finally, try inserting the Windows installation disc into the drive and starting it up. Select Troubleshoot (Windows XP) or go to the Advanced Recovery Options menu and select the Startup Repair option. Wait for the programs to finish running and restart your computer.
