IT’S NEVER DONE THAT BEFORE!A Guide to Troubleshooting Windows XPby John RossSan Francisco®indtb_TITLE_COPY.fm Page iii Friday, April 14, 2006 2:07 PM3WHAT TO DO WHEN WINDOWS WON’T STARTYou know the routine: Turn on the computer, a bunch of text scrolls past as the monitor warms up, you see a sequence of “Windows is loading . . .” screens, and then Windows starts. You have to wait a couple of minutes for everything to load, but eventually your familiar desktop fills the screen, and you’re ready to get to work. After the third or fourth time, you don’t even notice that it’s happening.But one day, for no obvious reason, Windows won’t load. Either the screen goes dark or one of the “Windows is loading . . .” screens stays there forever. Or worse, you get a Blue Screen error. Yikes! What happened?This chapter explains what normally happens when Windows starts and how to use several tools and techniques for troubleshooting when it just won’t start.INDTB_02.book Page 39 Friday, April 14, 2006 12:19 PM40 Chapter 3The Windows Startup SequenceEvery time you turn on your computer, the machine and Windows XP perform a series of actions, always in the same order: First, the read-only memory basic input/output system (ROM BIOS) performs a series of diagnostic tests to confirm that the processor and memory are working properly. Then it tests some of the computer’s other components, including the hard drive and the video display. When those tests are complete, the BIOS runs the first of a series of programs that lead to starting the full Windows operating system. In other words, the whole startup process uses a relatively simple program located on a memory chip to start other, more complex software in several stages. Power-on Self Test (POST)The power-on self test (POST) is the first thing that happens when you turn on the computer. During the POST, the central processor uses instructions in the BIOS firmware (software located in a memory chip on the computer’s motherboard) to confirm that the power supply is working properly, run some memory and hardware tests, find operating system software on a hard drive or some other storage media, and set the configuration options specified in the BIOS.When the computer detects a problem during the POST, it either dis-plays a text message that describes the error, or it sounds a series of beeps (actually, beep codes). If the problem is so serious that it will not allow the computer to work properly (such as a massive memory failure), the system will either lock up or turn off the computer completely. Some of these error messages halt the POST, so the message remains visible on your monitor screen, but others might scroll past before you can read them. To stop the text from disappearing, press the PAUSE BREAK key on the right of the normal keyboard. To resume the startup routine, hold down the CTRL key and press PAUSE BREAK again.Beep CodesIf the POST detects a memory problem or some other condition that keeps the video display from showing error messages, a beep code will sound within the first 30 seconds after you turn on the computer. If you hear a beep code, note the number of long and short beeps and the order in which they sound. See Appendix A for a list of common beep codes. Each type of BIOS uses a distinct beep code pattern, so it’s relatively easy to identify the problem that produced the code, even if you don’t know the brand of BIOS your computer is using.For example, if you hear one long beep followed by three short beeps, the computer has an AwardBIOS, and the POST has detected a memory problem; a 1-2-2-1 code (one beep, pause, two beeps, pause, two beeps, pause, one beep) indicates a keyboard problem on a PhoenixBIOS.INDTB_02.book Page 40 Friday, April 14, 2006 12:19 PMWhat to Do When Windows Won’t Start 41Some computer motherboards also display POST codes on an LED readout mounted on the board. You’ll have to remove the cover from the computer case to see this display. If your computer has such a display, you can find a list of codes in the manual or on the motherboard maker’s website.Initial Startup: What Happens When You Push the ButtonAfter the computer completes the POST built into the motherboard, it may run additional tests on some of the other components, including the hard drive and the video adapter. Each of these tests can produce its own set of error messages.When the POST is complete, the computer tries to load the operating system software stored on the hard drive (in this case, Windows XP), a floppy disk, a CD, or some other storage device.A problem can occur during initial startup for several reasons:There’s a disk in the floppy drive or the CD drive, but it does not contain the essential startup files.The designated startup disk is damaged, whether it be a floppy, CD, or hard drive.The hard drive has not been formatted.The hard drive has been damaged, or the startup data is corrupt.If the BIOS does not discover any problems, it locates the boot sector on the startup drive and runs a Windows boot loader program called ntldr (NT Loader or boot loader). Ntldr takes over control of the computer from the BIOS. (The filename ntldr is left over from the earlier version of Windows called Windows NT; hey, whatever works.)Run the Boot LoaderThe boot loader program loads a series of startup programs, instructs the central processor to handle 32 data bits at one time, and starts the file system that Windows will use to exchange data with the hard drive. Finally, the boot loader reads the boot.ini file that identifies the location of the operating system files and runs the ntdetect.com program to detect and configure the hardware connected to your computer.Detect and Configure HardwareWindows uses the information gathered by ntdetect.com to identify and configure the various hardware devices that it uses to send, receive, and store data. This includes the keyboard and mouse; disk drives and other data storage devices; the video adapter that controls the monitor display; the I/O (input and output) ports, including the serial, parallel, Ethernet, and USB ports; and any other input or output devices installed in the expansion slots on the motherboard. Ntdectect.com also reads certain information from the BIOS firmware, including the time and date.INDTB_02.book Page 41 Friday, April 14, 2006 12:19 PM42 Chapter 3Load the Windows KernelThe file ntoskrnl.exe in your Windows