Why does my computer say "Invalid system disk, replace disk and then press any key to enter"?


My computer will turn on and then show the sceen saver of compaq, but afterwards a black sceen comes on and all it saids is: invalid system disk, replace disk and then press any key to enter. I have no clue what that means. I thought maybe the hard drive might be full and that i might have to use some sort of disk to erase everything and restore the main programs that came with the pc. But no luck I couldn't find such disk in my storage kit. I've had this computer for six or seven years now. What do i do? How can i get on? I'm really poor and can't afford a new pc with the money i make nor take as many classes as i need in college! So please help me find the answer. Thank you


This question was answered on October 22, 2004. Much of the information contained herein may have changed since posting.

It sounds like there is a floppy in the A drive If there is remove it and restart your computer, problem fixed.

If that didnt work then the problem could be one of the following.

1 Your computer may be infected with a boot-sector virus such as the AntiCMOS A virus.

Use an anti-virus program to detect and remove the virus, and then reinstall Windows Boot-sector viruses infect computers by copying information either to the boot sector on a floppy disk or the partition table on a hard disk During startup, the virus is loaded into memory Once in memory, the virus typically infects any non-infected disks that your computer is connected to.

2 Your computer is running an anti-virus program

Start your computer by using the Windows Startup disk you created during Windows Setup, and then use the sys command from the Windows Startup disk to restore the system files to the hard disk

Some computers use built-in anti-virus software that must be disabled in the computer's BIOS For information about how to change settings in the BIOS, view the computer's documentation or contact the manufacturer of your computer.

3 Your computer is using hard disk management software (such as Disk Manager, EZ-Drive, or DrivePro) for hard disk geometry translation These tools provide support for large hard disks (more than 1024 cylinders) when your computer's Basic Input/Output System (BIOS) does not support large hard disks.

Computer Is Using Disk Management Software In some cases, Windows may not properly detect that you are using disk management software and may overwrite the master boot record (MBR) information Refer to the documentation for the disk management software you are using for information about restoring the MBR

Also, check the Setuplog.txt file for the following statement:

FSLog: BIOS Heads=:64:, BootPart Heads=:64:

The preceding number (64 in this example) may vary from computer to computer If these two numbers are different, replace the system files on your hard disk according to the instructions in the following "Reinstall the Windows System Files" section For additional information about how to determine if your computer is using a drive overlay program, click the article number below to view the article in the Microsoft Knowledge Base:

4 Windows Setup was unable to copy the system files to the hard disk.

WARNING: If you are using Disk Manager or any other disk drive overlay program on a hard disk, make sure that the overlay driver is loaded before you use the sys command on that hard disk If the overlay driver is not loaded and you use the sys command on the hard disk, the drive may not be recognized as being partitioned by the disk drive overlay program and you could experience loss of data or an inability to boot from the drive

Although you can use the sys command with On track Disk Manager and later versions of MicroHouse EZ-Drive (or EZ-Max) after the overlay driver is loaded, earlier versions such as EZ-Drive 2.01s require that operating system files be copied to the overlay installation disk and installed by the overlay utility In such cases, the overlay may be damaged if you use the sys command on the hard disk.

A Start your computer by using the Windows 95 or Windows 98 Startup disk.

B At the command prompt, type the following commands, pressing ENTER after each command:



attrib c:\msdos.sys -s -h -r

copy c:\msdos.sys c:\msdos.xxx


sys c:

attrib c:\msdos.sys -s -h -r

del c:\msdos.sys

copy c:\msdos.xxx c:\msdos.sys

attrib c:\msdos.sys s h r

C Remove the Windows Startup disk, and then restart the computer.

E Security software has disabled access to drive C.

Some third-party programs prevent (lock) access to hard disks in your computer If this software is installed, contact the manufacturer about how to remove this software and safely restart Windows 98 Setup For additional information about Windows Setup and troubleshooting steps, click the article number below to view the article in the Microsoft Knowledge Base:

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Posted by julie of Katharine Gibbs School - New York on October 22, 2004