Start pc in MS DOS

[Alex]

I think my computer has a virus in the boot sector and I
can't open explorer to get the to DOS prompt. How can I
start my computer in MS DOS so I can take action from
there?

Thanks

 

[null]

I think my computer has a virus in the boot sector and I
can't open explorer to get the to DOS prompt. How can I
start my computer in MS DOS so I can take action from
there?

Thanks

Hold down the F8 key while booting, and select Safe Mode Command Prompt.

--
The reader should exercise normal caution and backup the Registry and
data files regularly, and especially before making any changes to their
PC, as well as performing regular virus and spyware scans. I am not
liable for problems or mishaps that occur from the reader using advice
posted here.

 

[hal]

I think my computer has a virus in the boot sector and I
can't open explorer to get the to DOS prompt. How can I
start my computer in MS DOS so I can take action from
there?

Try hitting F8 after the manufacturers BIOS splash screen and before
the Microsoft splash screen. Try booting into safe mode with command
prompt. If that doesn't work you will need to set the floppy disk as
first device in your boot order in the BIOS setup and put in a
bootable DOS disk and boot off floppy.

Hal

 

[CS]

I think my computer has a virus in the boot sector and I
can't open explorer to get the to DOS prompt. How can I
start my computer in MS DOS so I can take action from
there?

Thanks

You "think" your computer has a boot sector virus? Are you using AV
software? If you really have a boot sector virus, opening a command
prompt as has been suggested already is not going to do any good since
the command prompt will be in protected mode. (DOS emulation)

To get rid of "some" (not all) boot sector viruses, boot the machine
to real mode DOS with a Win98 DOS disk. Doesn't make a difference if
your hard drive is formatted to NTFS..... Make sure the utility
fdisk.exe is on the disk.

From the A:> prompt issue this command: fdisk /mbr

That will write a new generic MBR to the hard drive and possibly
overwrite the virus and kill it. May or may not work.

 

[Bruce Chambers]

Greetings --

Not to put too fine a point on it, you can't.

There is no way to reboot a WinXP PC into Real Mode DOS unless
you've set up a dual-boot system. The WinNT family of 32-bit
graphical operating systems, of which WinXP is the latest generation,
has never used, included, or "ridden upon" MS-DOS. The closest they
have is the Command Prompt window.


Bruce Chambers
--
Help us help you:



You can have peace. Or you can have freedom. Don't ever count on
having both at once. - RAH

 

[Edward W. Thompson]

Surely he can boot his machine from a DOS floppy. If the machine is
formatted FAT32 he can run an AVP from the floppy.

Even with a dual boot system, if the Windows partition is formatted NTFS,
you cannot access it from DOS (NTFSDOS Pro excepted)

 

[NobodyMan]

On Fri, 20 Aug 2004 07:30:31 +0100, "Edward W. Thompson"

Surely you know that's not booting into DOS from XP.

 

[Incognitus]

That's not what the OP ask, the question was: "How can I start my computer
in MS DOS", not "booting into DOS from XP" and the answer is simply boot
with MS DOS startup disk, which I do weekly in order to run F-Prot for DOS
AV (yes I know the difference between FAT32 and NTFS) and may be what the OP
is looking for when he said "I think my computer has a virus in the boot
sector".

If the OP has FAT instead of NTFS as Edward W. Thompson suggested, then the
OP could run an AV, such as F-prot for DOS, to scan the boot sector.

Instructions and F-prot for DOS are here:
http://www.f-prot.com/products/index.html

 

[cquirke (MVP Win9x)]

On Sat, 21 Aug 2004 09:05:51 -0500, "Incognitus"

That's not what the OP ask, the question was: "How can I start my computer
in MS DOS", not "booting into DOS from XP" and the answer is simply boot
with MS DOS startup disk, which I do weekly in order to run F-Prot for DOS
AV (yes I know the difference between FAT32 and NTFS) and may be what the OP
is looking for when he said "I think my computer has a virus in the boot sector".

It's a good approach for just "I think my computer has a(n active)
virus", as long as you avoid NTFS and thus can scan the HD.

If the OP has FAT instead of NTFS as Edward W. Thompson suggested, then the
OP could run an AV, such as F-prot for DOS, to scan the boot sector.

You can anyway, but if NTFS, the pre-filesystem boot sectors (MBR,
PBR) are all you can scan.

Instructions and F-prot for DOS are here:
http://www.f-prot.com/products/index.html

Alternatives are free evaluation DOS av scanners at...
www.nod32.com
www.sophos.com
....but no updates for these, AFAIK.

This is true. Win9x includes a DOS mode alternate boot, and (like NT)
emulates DOS from within Windows. The Win9x DOS emulation is more
accurate and tolerant of DOS apps that access hardware directly.

The DOS mode from Win9x can be a useful maintenance environment for
NT, as long as HD < 137G and file system is FATxx.

See http://cquirke.mvps.org/multplan.htm on multi-boot strategies,
such as a FATxx C: that hosts both XP and a Win9x DOS mode.

Diskette boot. If you suspect a boot code virus (BSV), this is the
only safe way to tackle it. However, BSVs would be rare in NT systems
and would be unlikely to run in NT anyway, so I more likely something
else is going on, e.g. commercial malware hiding in IE or direct worm
attacks that penetrate unpatched, no-firewall NT.

--------------- ----- ---- --- -- - - -

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