A Stop error occurs, or the computer stops responding when you try to start Windows Vista or Windows 7

When you try to start Windows Vista or Windows 7, a Stop error occurs. Or, the computer stops responding.

This problem may occur in many scenarios. These scenarios include the following:

• The registry is corrupted.
• A System file is missing or damaged.
• A device driver file is missing or damaged.

To resolve this problem, use the Startup Repair tool. The Startup Repair tool can fix some problems that prevent the operating system from starting correctly.

You can run the Startup Repair tool by using the Windows Vista or Windows 7 installation disc or by using the computer's preinstalled recovery options.

To run the Startup Repair tool by using the Windows Vista or Windows 7 installation disc

If you have the Windows Vista or Windows 7 installation disc, follow these steps to use the Startup Repair tool:

1. Insert the installation disc.
   
   Note The computer must be configured to start from a CD or from a DVD. For information about how to configure the computer to start from a CD or from a DVD, see the information that came with the computer.
2. Restart the computer. To do this, click Start
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   , click the arrow next to the Lock button, and then click Restart.
   
   Note If you cannot restart the computer by using this method, use the power button to turn off the computer. Then, turn the computer back on.
3. Set your language preference, and then click Next.
   
   Note In most cases, the startup repair process starts automatically, and you do not have the option to select it in the System Recovery Options menu.
4. Click Repair your computer.
5. In the System Recovery Options dialog box, click the operating system that you want to repair, and then click Next.
6. In the System Recovery Options menu, click Startup Repair to start the repair process.
7. When the repair process is complete, click Finish.

To run the Startup Repair tool if the computer has preinstalled recovery options

If the computer has preinstalled recovery options, follow these steps to use the Startup Repair tool.

Note In most cases, the startup repair process starts automatically. Follow these steps only if Startup Repair does not start automatically.

1. Remove all floppy disks, CDs, and DVDs from the computer, and then restart the computer.
2. Follow one of these steps:
   • If the computer has a single operating system installed, press and hold the F8 key as the computer restarts. You must press the F8 key before the Windows logo appears. If the Windows logo appears, you must restart and try again.
   • If the computer has more than one operating system, use the arrow keys to select the operating system that you want to repair. Then, press and hold F8.
3. In Advanced Boot Options, use the arrow keys to select Repair the computer, and then press ENTER.
4. Click a keyboard layout in the list, and then click Next.
5. Click a user name in the list, enter the password, and then click OK.
6. In the System Recovery Options menu, click Startup Repair.
7. When the repair process is complete, click Finish.

Note The problem may not be resolved after the Startup Repair tool runs one time. If the problem is not resolved when the computer restarts, follow the steps again.

The Startup Repair tool automatically fixes many common problems. The tool also lets you quickly diagnose and repair more complex startup problems. When the computer detects a startup problem, the computer starts the Startup Repair tool. When the tool starts, it performs diagnostics. These diagnostics include analyzing startup log files to determine the cause of the problem. When the Startup Repair tool determines the cause, the tool tries to fix the problem automatically.

When a startup problem occurs and the Startup Repair tool cannot fix the problem, the system returns to its last known working state. If the Startup Repair tool cannot automatically recover the system, the tool gives you diagnostic information and support options to make troubleshooting easier.

The Startup Repair tool generates a log file to help you understand the startup problems and the repairs that were made. You can find the log file in the following location:Here, %windir% is the folder where Windows is installed.