Boot manager failed to find OS loader 0x490

Jesse Chen ‚ÄĘ October 23, 2010 ‚ÄĘ 6 min read


Background to the near catastrophic event#

Last night, I was modding my Motorola Droid with this sick theme called DarkEdge, to prepare to sell it to a lucky buyer.  In order to remove my Google account from the phone, however, required me to factory reset the phone.  Well, that turned out to not be a good idea because DarkEdge tampers with several files that custom ROMs normally don't touch [since DarkTheme is also a skin, not just a custom ROM], and as a result, I was stuck in a force-close loop.  Luckily, I can still turn on USB storage so I thought that to solve this simple problem would be as simple as downloading an file and booting into recovery to flash the firmware.  However, all the different ones I tried [FRG22d, CM 6.0, etc.] all failed the signature check, so the only way to go from here is to flash a .sbf file, which I have yet to do.

Catastrophic event#

That was the background to what I'm really getting to because downloading all those files from around the internets caused Microsoft Security Essentials to raise a flag that it detected a trojan on my computer!  I have never gotten viruses/trojans/worms before [at least, not that I have noticed :P], so when I was reading the description of this trojan, my computer suddenly shut down for no reason!  When I tried to boot up again, it went straight into the Windows 7 Recovery Mode.  It ran an automated startup repair, which I thought, OK good..usually this will just fix the boot sector or MBR and I'll be on my merry way.  However, this time around it threw the error "Boot manager failed to find OS loader" with "Error Code = 0x490".  Thus, when it restarted I was just brought back into the System Recovery Mode, and it did the same exact thing.  Over, and over.

Side note: I divided my HDDs into three partitions: OS, Applications, and Data.  I knew that in the event of catastrophic failure of the OS, setting up these partitions will allow me to retain my data if I have to reformat.  However, what I never knew was if I were to re-install the OS would I be able to not have to re-install all my applications.  If someone knows, please do tell.

I started freaking out because I never had this problem before, and I did not want to reinstall all 100 [exact, yes for real] applications that I have on my desktop.  System restore also did not work.  So, I opened up my laptop and began to search for answers online using my strong google-fu.  After trying multiple solutions, some of which are bogus, I finally found the correct one that allowed me to type this up on my desktop.  I am writing this down for posterity and to hopefully have this correct solution reach out to more folks who are suffering the same problem.  I will definitely be more vigilant with my backups and system recovery images from now on.


This is the link to the thread I found the answers, for reference and citation.  Kudos to momominimo.

If you don't have your Windows installation disc:

If you do have your Windows installation disc: (from hereon copy and pasted from source)

Bootrec.exe Options#


The **/**FixMbr option writes a Windows 7 or Windows Vista-compatible MBR to the system partition. This option does not overwrite the existing partition table. Use this option when you must resolve MBR corruption issues, or when you have to remove non-standard code from the MBR.


The **/**FixBoot option writes a new boot sector to the system partition by using a boot sector that is compatible with Windows Vista or Windows 7. Use this option if one of the following conditions is true:


The **/**ScanOs option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option displays the entries that are currently not in the BCD store. Use this option when there are Windows Vista or Windows 7 installations that the Boot Manager menu does not list.


The **/**RebuildBcd option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option lets you select the installations that you want to add to the BCD store. Use this option when you must completely rebuild the BCD.

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