This really is a DOS question, so bear with me: Our Compaq Presario 2100 won't boot (running XP Home for a couple of years now)--we get a box saying it can't find "lsass.exe". No luck booting in any of the alternate modes, either--same message.

Can't use the QuickRestore disk set 'cause that reformats the HD, and we need data that's been stored since our last backup. So that won't help.

I don't think this is hard-drive failure but rather a fluke deletion or file rename due to our cat walking on keybd (seriously). If that's the case, I wondered if it would be possible to make a DOS boot disk, boot the Compaq to DOS and then copy the missing file (from another of our XP computers) to its normal LOCATION on the Compaq.

So...I've made a bootable DOS CD (6.22), using the bfd/bfl instructions. And the Compaq does indeed boot to DOS. **Problem is** the computer comes up under drive R or A, but regards C as an invalid drive letter. And I don't know the DOS command to tell the computer to shape up and find C!

Other than the missing lsass file, the hard-drive is working normally--as verified by watching how fast files loaded when trying to boot into Safe mode--but still can't find a command to get it to recognize C:. From reading the command syntax and functions I don't think Assign and Subst will solve anything, so...any ideas would be greatly appreciated.

Thx. --sfThe Windows partition is given the letter C by XP Home but your DOS disk but it will not appear at all to a DOS boot disk if the file system is NTFS. (DOS does not read NTFS)

Have you looked in drives A and R?


You may have several options:

One option is insert your original WindowsXP CD, and boot the computer.
Hopefully you will get an option to GO to a repair mode. XP will attempt to replace the missing or corrupt files. I have used this option successfully, but it's been a while and I can't remember the details of how to get to the menu and what to do when there. Maybe someone else can fill you in on this option, or Google "Windows XP Repair" and read up on it.
I think I would try the repair before I went messing around copying the file manually, but if you want to do that, here is option 2:


Go to:
www.nu2.nu/pebuilder/
and make a Bart's PE boot cd from your WindowsXP cd. This boot cd will recognise your NTFS partition and better yet if you are not good in DOS, it is Windows XP along with the GUI you are more familiar with.(maybe a stripped down version of XP, but XP nonetheless) Instead of My computer or Windows Explorer, you will be using the "a43 File Management Utility"

See the recent thread named :
"copy large files from unformated/unknown partition" started by marcusb
(His problems were much WORSE than yours.)


If you get the operating system booting up again, great! Otherwise see option 3.


Similar to option 2, the Bart's PE boot is your best bet for getting your data (that you never backed up before) backed up now. Then you can use the restore disks, or whatever to reload a new operating system.
Thanks to both of y'all--good points, good info.

Dias: I'd forgotten that XP typically (or is it always?) uses NTFS, and that DOS can't read it. But I would have thought that DOS would recognize the *physical device*, even if it couldn't read any data from it. But that's what I get for thinking.

Drives A and R: A: is a virtual device created in RAM by the CD. The Bart-disk guy noted that lots of new 'puters don't have floppy drives, so he needed a workaround. The A drive holds DOS, in a dozen or so directories that I didn't recognize. Some of these directories contain ".cab" subdirectories, so I suspect there's a lot of higher-level capability there if I just knew the magic words.

The R drive seems to be just two files, one of which is the missing lsass.exe that I added to the CD in case I could copy it. I forget the other, but it was only 1Kb or so, and may have been an autoexec.bat that created the virtual A drive and loaded DOS to it.

LLMeyer: Option One seems very attractive but unfortunately the Compaq, like most machines that came preloaded with XP, doesn't have a Windows CD as such. Instead the info on the CD is loaded on the hard drive at the factory. Then the image file unpacks itself as the XP OS.

Though we don't have an XP CD as such, we do have a set of 4 "QuickRecovery" CDs, and it *may* be that if you insert one it may give you the option of just scanning for any missing XP files. I think that's the feature you used once before. But the manual said the QR utility would re-format the HD, so I was reluctant to pop it in just in case it had an autorun on it and wouldn't give me a choice. Yeah, I realize that's unlikely but I've run into crap like that before!

Tried making a Bart's PE bootable CD from another XP machine (different mfr) but Bart's instructions say that using an "OEM version" of XP to make a boot CD almost never works--and sure enough, it didn't. Evidently there's a machine-specific file on OEM versions that prevents the OS from booting other machines. Understandable.

Since at this point it seems there's no way to boot the Compaq with enough functionality to permit copying the missing file to C:, I considered one other idea that was a longshot but...: What about removing the Compaq's HD, putting it in our XP desktop, and then explore it like any other hard drive? Since I wouldn't be needing it to boot up the desktop, the missing file shouldn't be a problem.

So...anybody heard of the adapter? Or why moving the HD to the desktop won't fly? Thanks. --s
I realize the connectors on notebook drives are different from those on standard HDs but surely there's an adapter to enable their use. At least, I'd think so.Quote from: sf44

Since at this point it seems there's no way to boot the Compaq with enough functionality to permit copying the missing file to C:, I considered one other idea that was a longshot but...: What about removing the Compaq's HD, putting it in our XP desktop, and then explore it like any other hard drive? Since I wouldn't be needing it to boot up the desktop, the missing file shouldn't be a problem.

So...anybody heard of the adapter? Or why moving the HD to the desktop won't fly? Thanks. --s
I realize the connectors on notebook drives are different from those on standard HDs but surely there's an adapter to enable their use. At least, I'd think so.

Very common practice in data recovery.

The LSASS process manages user logins, and as such is a common target for infections on PCs running various versions of Windows.

Here's a description of this virus from Trend Micro:

"This worm exploits the Windows LSASS vulnerability, which is a buffer overrun that allows remote code execution and enables an attacker to gain full control of the affected system. To propagate, it scans the network for vulnerable systems. When it finds a vulnerable system, this malware sends a specially crafted packet to produce a buffer overflow on LSASS.EXE. This worm can cause LSASS to crash and FORCE Windows to restart."

I was able to d/l the NTFS4Dos utility, make a DOS boot disk and explore the hard-drive.