There could be any of the following possibilities.
- Software Issue
- Hardware Issue
- Heat Related Issue
- Computer Virus Problem
- Operating System Issue
Errors generated by software programs can cause a computer to reboot unexpectedly or without warning.
To test this, boot your computer into Safe Mode. If the computer is still rebooting in Safe Mode the issue is likely not software related. Windows XP is designed to automatically reboot each time an error occurs. Below are the steps on how this feature can be disabled and enabled in Windows XP.
- From the desktop right-click on My Computer.
- Click the Properties option.
- In the System Properties window click the Advanced tab.
- In Advanced click the Settings button under Startup and Recovery.
- In the Startup and Recovery window uncheck the Automatically restart check box.
- Click Ok.
Now if the computer generates error, it should not automatically restart and enable you to display any errors your computer may be experiencing.
Any failing hardware component in your computer could cause your computer to unexpectedly generate an error and/or reboot without warning. If you have recently attempted to add a new hardware device, remove that device to make sure it is not causing your issues. New drivers can also cause this issue, if you have recently performed any hardware driver updates you may wish to try an earlier version of the drivers.
If you have updated drivers and removed any hardware that could be causing this issue and continue to experience random reboots, it’s possible that the memory is bad in the computer. Hardware devices that are not installed properly in the computer can also cause random reboots. Make sure all the cables and expansion cards are connected properly to the computer. The best way to determine this is to disconnect and reconnect all cables and expansion cards.
Computer Virus Problem
Computer viruses such as the blaster virus are written to reboot your computer without warning. Usually these viruses will make the computer reboot ever 5, 10, 15 or 30 minutes after the computer has started. If you believe your computer may be infected with a virus or are uncertain if your computer is infected with a virus make sure your virus scanner definitions are up to date.
Heat Related Issue
Many computers today are designed to turn off or automatically reboot if the computer, processor, or other device in your computer gets hot. If you have heard any abnormal noises coming from your computer recently such as a high squealing this could indicate a fan may be failing in your computer which will result in temperature increase of your computer. You can first start by verifying the fan on the power supply is working by examining the back of the computer and seeing if the fan is moving smoothly and working properly. For all other fans in the computer you will need to either open the computer and make sure the fan are working (processor fan and case fan) and/or if your BIOS monitors the RPM of the fans enter BIOS and make sure the BIOS does not report any errors.
Users may also be able to determine how hot their computer is by onboard thermal sensors, if your computer comes equipped with these sensors make sure your CPU is not running to hot.
Operating System Issue
If after following each of the above recommendations your computer still continues to reboot it is likely that you are experiencing a Microsoft Windows operating system related issue. Reboot the computer and enter CMOS setup as the computer is booting. After you have loaded the computer in CMOS setup let the computer sit. If the computer does not reboot it is likely that you are in fact experiencing an issue with Microsoft Windows and it is recommend that if you have followed all of the above recommendations that you reinstall your version of Microsoft Windows or update your windows files.