Windows Registry: Deleting from HKLM\MY_SYSTEM

The “HKLM\MY_SYSTEM” may be in use by the operating system. If the goal is to remove some of that information, see these directions for deleting from HKLM\MY_SYSTEM. (Note that this is not particularly common, so there's no need to follow those instructions unless that specific task is desired.)

This will require rebooting out of the main installed copy of Windows. Fortunately, an alternate partial installation may be readily available and may also be quite sufficient.

Know a password for an Administrator account on this system. That password won't be needed immediately, but it will be needed eventually.

First, make a batch file. (This simply involves using a text editor and making a file that ends with the extension “.BAT”. Here is a sample file, which does not need to be customized in most cases:

@Echo Off
CD /D %~dp0
CD \
Reg LOAD HKLM\MY_SYSTEM "\Windows\System32\config\system"
\Windows\System32\shutdown /r /t 0 /d p:2:4 /c "Removing unhelpful data"

Place this batch file on the same drive letter as the copy of Microsoft Windows that is going to have its registry altered. The batch file should be placed on that drive so that the reference to %~dp0 works as intended. (By the way, referring to %~dp0 from inside a text filemay work different than referring to %~dp0 from a command line, so if you want to try using an echo statement for test purposes, doing so from a text file is recommendd.)

Furthermore, it is recommended (though not absolutely required) that the batch file be placed in the root directory of that drive, so that the file can be accessed easily.

Back up the registry. (Instructions for backing up the registry, or restoring it if there are problems, are not included here at this time. This guide is simply recommending this as a general practice that is good to do in this sort of case.)

Create a system restore point. (info...) .....

You may wish to run msconfig and access the “Boot” menu, in order to make sure that there is a reasonably long “Timeout:” value. Also check some of the checkboxes in the “Boot options” section (but not the “Make all boot settings permanent” checkbox), so that there is clearly some choice to be made. If they are all cleared, Microsoft Windows may be more prone to skip prompting the user about how to boot. (All of the checkboxes in the “Boot options” section can be checked, if desired.)

Next, become familiar with the upcoming instructions. The basic goal is to get to access the Advaned Boot Options.

Booting with Advanced Boot Options
Windows 7

Reboot. (If you still have the batch file open, you can just choose to run the last line of the batch file. That will reboot.)

As Microsoft Windows starts to boot up, hold either F3 (as noted by icc97's answer to Clare Macrae's question) or F8.

After a menu comes up, if you held F8, you may see an extra menu or two. If you have a chance to choose your operating system, highlight the operating system that you wish to affect. Then, follow the instruction that states, “To specify an advanced option for this choice, press F8.” Pressing that key will advance to the “Advanced Boot Options” menu for that operating system.

If you held F8, you'll arrive at the “Advanced Boot Options” menu. From there, choose “Repair Your Computer”.

Windows 8

Users of Windows 8 may benefit by reading some additional tutorials; perhaps see How to enable/disable Advanced Boot Manager in Windows 8 and/or 3 ways to access Windows 8 boot options menu.

When requested to log in, make sure to choose an account that has Administrator privileges.

You should then arrive to the “System Recovery Options” screen. (This is documented by Microsoft at: What are the system recovery options in Windows?

Find the batch file.

dir *.bat

Run the batch file.