Recently my PC has starting shutting down on its own. It then attempts to start, gets so far and then shuts down again, before trying to restart. After pulling the plug (at the wall) and leaving it for a wee while, it seems to work OK. However, it is now starting on its own. I haven't seen any error messages, apart from one about Windows not shutting down properly during start-up.I've had a look inside the machine and cleaned it out. I've also disconnected a second CD/DVD drive that I thought might be part of the problem. I've also run a virus checked which found a couple of Trojans but removing them didn't fix the problem. The machine is a Dell Dimension 3100.Any help appreciated.

Hi jrellis222, Method 1:You may refer to the below article and check if you can access the help section in safe mode in Windows XP. Refer to the below article to boot in safe mode - http://support.microsoft.com/kb/315222 Method 2:I would suggest you to follow the steps provided in the links and boot the computer by using the F8 key and from the advanced startup options. Select the option to disable automatic restart on system failure.This prevents Windows from automatically restarting if an error causesWindows to fail. You may choose this option ifWindows is stuck in a loop whereWindows fails, attempts to restart, and fails again repeatedly.You might get a BSOD (Blue screen of death) after disabling automatic restart. Blue screens (BSOD’s) are mostly due to hardware and sometimes due to incompatible software. In a lot of cases it is a corrupted driver or a driver conflict. The most common causes of blue screens are overheating, faulty RAM, and video card problems The above steps will let you see the BSOD message when the system restarts and will allow you to write down the full message. You will need to turn off the computer manually afterwards.Try to note the exact error message you are getting and notify us about it to assist you better.Method 3:If the issue persists you may check if you face the same issue in a clean boot state. This will help identify which service is causing the issue. To perform the clean boot follow the step 1 mentioned in the below article and then try checking in this clean boot state -http://support.microsoft.com/kb/310353If the issue gets resolved check which non-Microsoft service or program is causing the problem; referring to the article and following other steps.After you have finished troubleshooting, follow these steps to reset the computer to start as usual:a. Click Start, type msconfig.exe in the Start Search box, and then press ENTER.If you are prompted for an administrator password or for confirmation, type your password, or click Continue.b. On the General tab, click the Normal Startup option, and then click OK.c. When you are prompted to restart the computer, click Restart.Method 4:You may even check if you are getting any errors in the Event viewer and if you are getting any, do let us know the details. To open event viewer follow the below mentioned steps:a. Click the Start button then click Control Panel in this click System and Maintenance.b. Now click Administrative Tools, and then double-click Event Viewer.‌ If you are prompted for an administrator password or confirmation, type the password or provide confirmation.c. Click an event log in the left pane.Double-click an event to view the details of the event. You may also refer to the below link –http://support.microsoft.com/kb/308427Hope this helps.Thanks,Meghmala – Microsoft SupportVisit our Microsoft Answers Feedback Forum and let us know what you think

With regard to the above problem, I removed the USB audio power board (MC186) from the computer and cleaned it. There must have been some short across the board that was turning the machine on and off. Cleaning and replacing the board has fixed the problem.

Hello, Good to know the issue got resolved. Do let us know if you face any issues with Windows operating system in future.Regards,Meghmala – Microsoft SupportVisit ourMicrosoft Answers Feedback Forum and let us know what you think