The Dreaded BSOD

The Blue Screen of Death (BSOD) is the screen displayed by Microsoft's Windows operating system when it cannot (or is in danger of being unable to) recover from a system error. There are two Windows error screens that are both referred to as the blue screen of death, with one being significantly more serious than the other.

The blue screen of death in one form or another has been present in all Windows operating systems since Windows version 3.1 until about 2001 with the release of Windows XP.  It is considered a built in "feature" of Windows and is related to the black screen of death in OS/2.

In early builds of Windows Vista (formerly known under the project name of Longhorn)  Microsoft added the red screen of death, used for boot loader errors but it was later removed.

The blue screen of death also occurs in Microsoft's home desktop operating systems Windows 95, 98, and Me. Here it is less serious, but more common. In these operating systems, the BSOD is the main way for virtual device drivers to report errors to the user. It is internally referred to by the name of "_VWIN32_FaultPopup". A Windows 9x/Me BSOD gives the user the option to either restart or continue. However, VxDs do not display BSOD frivolously?they usually indicate a problem which cannot be fixed without restarting the computer, and hence after a BSOD is displayed the system is usually unstable or unresponsive.

The most common reason for BSOD's is problems with incompatible versions of DLLs. This cause is sometimes referred to as DLL hell. Windows loads these DLLs into memory when they are needed by application programs; if versions are changed, the next time an application loads the DLL it may be different from what the application expects. These incompatibilities increase over time as more new software is installed, and is one of the main reasons why a freshly-installed copy of Windows is more stable than an "old" one.

In Windows 95 and 98, a BSOD occurs when the system attempts to access the file "c:\con\con". This is often inserted on websites to crash users' machines. Microsoft has released a patch for this.

The BSOD can appear if a user ejects a removable medium while it is being read on 9x/ME. This is particularly common while using Microsoft Office, if a user simply wants to view a document, he might eject a floppy disk before exiting the program. Since Microsoft Office always creates a temporary file in the same directory, it will trigger a BSOD upon exiting because it will attempt to delete the file on the disk that is no longer in the drive.

This type of blue screen is no longer seen in Windows NT, 2000, and XP. In the case of these less serious software errors, the program may still crash, but it will not take down the entire operating system with it due to better memory management and decreased legacy support. In these systems, the "true" BSOD is seen only in cases where the entire operating system crashes.

What you see will look like this in Windows 95/98 and similar in Windows ME




   A fatal exception 0E has occurred at 0157:BF7FF831 in VXD VMM(01) +
   00010E36. The current application will be terminated.

   *  Press any key to terminate the current application.
   *  Press CTRL+ALT+DEL again to restart your computer. You will
      lose any unsaved information in all applications.

                         Press any key to continue