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Invalid Partition Table after Fdisk /mbr

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10 replies

by jctech 1 view

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I'm working on a system that had a Windows 95 upgrade (OSR1). The hard drive is infected with Stoned.Monkey.F, which modified the master boot record. In attempting to clean it out, I booted with a windows95 boot disk, then did an fdisk /mbr to repair the boot sector. Now when I try to boot, I get an invalid partition table message. Is there any chance of recovery from this, or is it now time to repartition and reformat?

10 replies

by william jay

Not that it will help much now, since you can't get there to do it over again anyways ... From where did you invoke the fdisk /mbr command? From the bootdisk or from the \%windir%\command\ directory? And which file system is it formatted for, FAT16 or 32?
As to the chances of recovery, it is possible to install it as the second drive in a machine with Partition Magic installed and try to fix it with PM, (yes, it really does work magic sometimes) ...

by jctech

Could not tell from viewing the partition table what it was formatted for, since the partition table had been modified by the virus. It was showing 4 non-DOS partitions of ridiculously large sizes on a 540MB drive.

by parbo

Most likely the virus has done more damage then just the bootsector. if both partitions are corrupted it will be hard to retreive an data from the drive. i have used Lost and Found a couple of times to retrieve info from a failed disk also tiramisu seems to be very good in that. Give them a shot if you have info that you would like to keep. If not make life "easy" and repartition and reload.

by jctech

I'm just looking for a way to undo the fdisk /mbr if that is possible. The pc was booting to windows before and was able to access programs, except for getting illegal error when trying to open Internet Explorer 5.0. Also, hard drive was operatingin MS-DOS compatibility mode due to the virus boot sector mod. I'm looking for a way to return to that state and try again to restore the boot sector.

by dbld

I dealt with that particular virus in the past and had the same problem. I believe you will need to repartition and reformat. It sounds as if when you did it the first time the virus transferred (or was already on) the boot floppy. Create a new clean boot floppy and write protect it. This virus is memory resident so after you boot and fdisk shut down the machine for a few seconds to be sure the memory is clear. Good luck

by jctech

The boot floppy was write-protected so I don't think there's any chance the virus could have written to it.

by dmessner

One thing to thing about, to go along w/ the new boot disk. To remove memory residant viruses you can take the battery off the motherboard, wait 15 minutes, plug it in and reboot. You might need to reset BIOS setting or atleast go into the BIOS and save out of it, since you will be prompted to enter BIOS on first boot.

Not sure how this information helps at this point, but would have been nice to do before the Fdisk /mbr.

Good Luck.

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