Sunday, January 9, 2011

Window Safe Mode

Safe mode is a troubleshooting option for Windows that starts your computer in a limited state. Only the basic files and drivers necessary to run Windows are started. The words Safe Mode appear in the corners of your monitor to identify which Windows mode you're using.

There are several things that happen when Windows boots in Safe Mode that differ from a standard boot:

  • Safe Mode does not run the autoexec.bat or config.sys files.
  • Most device drivers are not loaded..
  • Safe Mode uses standard VGA graphics mode. This mode is supported by all Windows-compatible video cards.
  • Himem.sys, which is normally loaded as part of the config.sys script, is loaded with the /testmem:on switch. This switch tells the computer to test the extended memory before continuing.
  • Safe Mode checks the msdos.sys file for information on where to find the rest of the Windows files. If it finds the files, it proceeds to load Windows in Safe Mode with the command win /d:m. If it does not find the Windows files, it will run command.com to bring up a C: prompt.
  • Windows boots using a batch file called system.cb instead of the standard system.ini file. This file loads the Virtual Device Drivers (VxDs) that Windows uses to communicate with the standard parts of the computer.
  • Windows now loads the regular system.ini file plus win.ini and Registry settings. It skips the [Boot] (except for the shell and device lines) and [386Enh] sections of system.ini and does not load or run any programs listed in win.ini.
  • The Windows desktop loads up in 16 colors and at a resolution of 640 x 480 with the words "Safe Mode" in each corner.

Safe Mode starts up automatically if Windows does not boot on the previous attempt. You can also invoke Safe Mode by pressing F5 or by pressing F8 and selecting it from the boot menu.

Registry Key for Safe Mode:

“HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal”