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kahlil88

Laptop won't boot

12 posts in this topic

Someone brought a laptop to the computer repair shop I work at, and initially the problem was that it was stuck in a reboot cycle regarding a PBR error and "NTLDR not found". The hard drive passed the SeaTools long test and I ran a filesystem check from the OS disc. After that, it hung at "loading PBR for descriptor" so I tried running FIXMBR, FIXBOOT and then did a repair install because it just hung with a blinking cursor. Even after another repair install and trying FIXMBR/FIXBOOT again, it still just hangs at a black screen with a blinking cursor.

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Someone brought a laptop to the computer repair shop I work at, and initially the problem was that it was stuck in a reboot cycle regarding a PBR error and "NTLDR not found". The hard drive passed the SeaTools long test and I ran a filesystem check from the OS disc. After that, it hung at "loading PBR for descriptor" so I tried running FIXMBR, FIXBOOT and then did a repair install because it just hung with a blinking cursor. Even after another repair install and trying FIXMBR/FIXBOOT again, it still just hangs at a black screen with a blinking cursor.

The blinking cursor is typical of:

  • wrong data in bootsector (PBR)
  • conflicting CHS vs. LBA (that also causes the above) on some BIOSes

The "loading PBR for descriptor" is NOT a message in standard MBR (meaning NOT a standard 2K/XP one), it should mean that original user has installed a "custom" MBR of some kind, like a bootmanager of something like it.

The problem is usually fixable but I will need to see BOTH the MBR and the PBR of the boot partition.

HDhacker is handy to make such images:

http://dimio.altervista.org/eng/

See here for a quick howto for HDhacker use:

jaclaz

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The blinking cursor is typical of:

  • wrong data in bootsector (PBR)
  • conflicting CHS vs. LBA (that also causes the above) on some BIOSes

If I may add, also

- no active partition.

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If I may add, also - no active partition.
That was one of my initial thoughts, but I checked it out with GParted and FDISK and the Windows partition is definitely set as active. I'm also considering the possibility of a boot sector virus. I scanned the drive with HDHacker and (after some garbage characters) it said "A disk read error occurred...NTLDR is missing...NTLDR is compressed...Press Ctrl+Alt+Del to restart"

Edited by kahlil88
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I scanned the boot sector with HDHacker and (after some garbage characters) it said "A disk read error occurred...NTLDR is missing...NTLDR is compressed...Press Ctrl+Alt+Del to restart"

You don't "scan" anything with HDhacker :w00t:, you use it to make a copy of the MBR and of the PBR and you post them.

Under Linux you can use dd allright for this. (but since you think that hex code is "garbage" :ph34r: I doubt that you are familiar with dd usage :unsure:)

jaclaz

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Here are the PBR and MBR images. Hope I did this right. Thanks.

Sure, the files are allright. :)

The contents may not. :unsure:

It seems like there is (I would say "was") a DELL recovery partition (partition ID "DE") 96327 sectors in size (i.e. 96327x512=49319424 bytes).

But it is missing the corresponding "DB" one.

It seems to me "strange" that such a small "service" partition exists without the "big" one.

The CHS and LBA seem like "balanced", but the partitioning does not respect Cylinder boundaries, which on some BIOSes may cause a problem.

(edited: no, the boundaries are respected also)

Definitely by doing all you did to that laptop you have replaced the "peculiar" Dell MBR with the ""standard" 2K/XP one, it is possible that the original Dell one could work with the broken boundary and the standard XP MBR doesn't.

(edited: but it is higly improbable)

Post some info on the actual hardware, maybe there is a fix on the manufacturer0s site (Dell), there are several types/versions of those partitions:

http://www.goodells.net/dellrestore/

Have you checked to e actual filesystem (with CHKDSK)?

jaclaz

Edited by jaclaz
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2nd try. A blinking cursor can also be caused by

-more active partitions.

Like if you restore the image of an active partition next to an other already active partition. I'm pretty sure of that.

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Post some info on the actual hardware, maybe there is a fix on the manufacturer0s site (Dell), there are several types/versions of those partitions:

http://www.goodells.net/dellrestore/

Have you checked to e actual filesystem (with CHKDSK)?

Running CHKDSK was the first thing I did after the drive passed the SeaTools long test. If I remember correctly, that got it out of the reboot cycle but then it just hung at "Loading PBR for descriptor" (it had this error before, but it was hard to read because it flashed quickly on the screen, then the NTLDR error and rebooted).

The machine is a Dell Inspiron 600m, and it appears Microsoft Security Essentials found something malicious on the drive, but I'm still waiting for the scan to complete.

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2nd try. A blinking cursor can also be caused by

-more active partitions.

Like if you restore the image of an active partition next to an other already active partition. I'm pretty sure of that.

But the partition table in the MBR Kahlil88 has a single visible partition, set Active. (and a Dell "service partition" hidden and NOT active)

@kahlil88

When you have finished, can you try running CHKDSK again and report?

jaclaz

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Connected the drive to our tech machine and removed a few viruses with Microsoft Security Essentials. Put it back in the laptop and it's booting fine now.

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