Troubleshooting Specific Startup Errors

This section describes specific conditions that might interfere with starting a Windows 95 computer and how to fix them.

In general, for system startup problems, the first problem-solving method is to start Windows 95 in Safe Mode. For information about how to start in Safe Mode and use BOOTLOG.TXT for troubleshooting, see Chapter 35, "General Troubleshooting."

Windows 95 stalls during the first restart after installation.

Usually this occurs because of legacy hardware that was configured incorrectly before Windows 95 was installed. Remove settings for hardware services in CONFIG.SYS and AUTOEXEC.BAT. Also, ensure that any SCSI devices are terminated correctly. You might also need to disable the ISA enumerator. This software detects a new type of adapter that can be configured from the operating system. The detection sequence requires the ISA enumerator for I/O processes on some ports. Although every effort has been made to avoid ports commonly in use, you might have hardware that is also trying to use these I/O ports.

To disable the ISA enumerator

Bad or missing file error occurs on startup.

If you receive a "Bad or missing filename" message when the system is starting (where filename might contain HIMEM.SYS, IFSHLP.SYS, and so on), do the following:

If the filename to which the message refers is a device driver the computer needs for accessing the drive where Windows 95 is installed, you need to move the device= line that contains the device driver to the beginning of CONFIG.SYS to allow access to the drive when CONFIG.SYS tries to load files from the Windows directory.

Windows 95 has damaged or missing core files.

When Windows 95 loads, it counts on key files being available and undamaged. If a system file is damaged or missing, it might prevent loading or normal operation. If VMM32.VXD or other core files are missing or damaged, you might need to run Windows 95 Setup and select the Verify option in Safe Recovery to replace the files.

System Registry file is missing.

The Windows 95 Registry file is required for operation. This is contained in SYSTEM.DAT and USER.DAT, which are backed up as .DA0 files. If only the SYSTEM.DAT Registry file is missing, Windows 95 does one of the following:

If both SYSTEM.DAT and SYSTEM.DA0 files are missing (or if the WinDir= entry in MSDOS.SYS is not set), a message informs you that the Registry file is missing and that Registry services are not available for this session. (This means that most operations in Windows 95 will fail.) After this message appears, Windows 95 automatically starts in Safe Mode and displays another message offering an option to restore the Registry. However, if there is no .DA0 file, the Registry cannot be restored. To resolve this problem, either restore SYSTEM.DAT from backup or run Windows 95 Setup.

For information about backing up and restoring the Registry, see Chapter 33, "Windows 95 Registry."

BIOS or a BIOS setting is incompatible.

A ROM BIOS setting might prevent Windows 95 from installing or loading, because some computers have a feature that prevents applications from writing to the boot sector. This is usually in the form of anti-virus protection set through your computer's CMOS. If this is enabled, Windows 95 cannot complete the installation or cannot start properly.

If boot sector protection is enabled in the computer's BIOS, one of the following symptoms occurs:

To correct this problem, disable the Boot Sector protection feature through your computer's CMOS, then reinstall Windows 95. For information about disabling this feature, consult your hardware documentation or service center.

VxD error returns you to the command prompt.

If a VxD is missing or damaged, Windows 95 displays an error message that indicates which VxD is involved. If the VxD is critical to the operation of Windows 95, then Windows 95 does not start and the screen displays the command prompt. You might need to run Windows 95 Setup and select Verify or Safe Recovery to replace the missing VxD.

You can selectively override a VxD that is included within VMM32.VxD. If the same VxD is loaded twice, the second instance intercepts all the calls to that particular VxD. There are two ways to override this:

You cannot use dual boot to run a previous operating system.

To take advantage of the dual-boot support in Windows 95, you cannot install Windows 95 into an existing Windows 3.x directory, and the value BootMulti=1 must be defined in the Windows 95 version of MSDOS.SYS.

DR DOS and versions of MS-DOS earlier than 5.0 do not support Windows 95 dual-boot functionality. To return to your previous operating system, you have to remove Windows 95 and reinstall your previous operating system, as described earlier in this chapter.

"Previous MS-DOS files not found" message appears.

When trying to dual-boot to the previous version of MS-DOS, you might receive an error message stating that your previous MS-DOS files were not found. It is probable that either the files are missing, or that your previous version of MS-DOS was not version 5.0 or higher.

You must have MS-DOS 5.0 or higher in order to start to a previous version of MS-DOS. Any version of MS-DOS earlier than 5.0 looks for the first three sectors of the IO.SYS file in the first three sectors of the data area of the drive. In MS-DOS 5.0 or higher, IO.SYS is designed to allow itself to be located outside the first three sectors of a drive's data area. In this situation, the only way to start to a version of MS-DOS prior to 5.0 is from a startup floppy disk.

Drivers, such as DBLSPACE.SYS, that are loaded when you start the computer using the earlier version of MS-DOS might not be available.

Required real-mode drivers are missing or damaged.

The previous operating system might have required certain real-mode drivers (compression, partitioning, hard disk drivers, and so on), and does not start correctly without them.

Windows 95 doesn't recognize a device.

In some cases, Windows 95 is unable to recognize an installed device, and the device resources are unavailable to Windows 95. If Windows 95 doesn't recognize an installed device, remove it in Device Manager, and reinstall it by using the Add New Hardware option in Control Panel. You can also use Device Manager to check resource conflicts. For information, see Chapter 19, "Devices." Or see the hardware conflict troubleshooting information in online Help.

Installing drivers causes Windows 95 system startup to fail.

If you try to install drivers for Windows 3.x from other vendors over Windows 95 (such as sound or video drivers), running the provided installation program can cause Windows 95 to fail to start or operate correctly.

To recover, when using a device that is supported by Windows 95

  1. Remove all entries in SYSTEM.INI that were added by the installation software from another vendor.
  2. Delete the device in Device Manager in the System properties, as described in Chapter 19, "Devices."
  3. Shut down and restart Windows 95.
  4. Use the Add New Hardware option in Control Panel to reinstall the device by using the Windows 95 drivers.
The wrong applications run after Windows 95 starts.