Fixing PartMgr.sys – PartMgr Failing to Start

After initially installing XP and transitioning it across multiple platforms over the years (not to mention all the SP updates on top of that), I found the other day a few low level, boot time devices that were failing to load or ‘Start’ correctly (i.e. Code 24 marked with an exclamation point when viewing Hidden Devices->Non-Plug and Play Drivers in Device Manager).  Now, many of these were devices that were no longer even installed in the machine, so the fix for them was easy, uninstall them.   Many of these were former drive and/or RAID controllers.  While uninstalling them however, I noticed that PartMgr, an integral part of the Windows OS, and an important one as it controls how Windows communicates with all of your partitions, was still sitting there with an exclamation point, and an error that stated that the driver couldn’t start, was not present, etc., etc.  When looking at its Properties, things became even more confusing as the Driver tab was telling me that the driver/device was started at boot-time, however was still stopped, not present, and failing for whatever reason.  Searching the Internet, I came across a lot of people that have run into this issue, but not one that actually got the issue corrected.  Being that re-installing Windows, doing an “in place, upgrade” was not an option, I dove into the issue and got things fixed up.  For those out there that might run into the same, here’s how to correct it. . .

I’ll take it you know you have the issue.  If you’re not sure but with high disk usage, probing around your file system and having Explorer lock up or do strange things, you might want to check.  To check, reference how above using Device Manager.  Remember, you must ‘Show Hidden Devices’ via the ‘View’ menu.  Once identified, here’s the steps…

  • Access REGEDIT (you can run this from the ‘Run’ menu, located within the Start Menu) and locate the following key:  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E967-E325-11CE-BFC1-08002BE10318}
  • You will notice in the right-hand pane a ‘Name’ of string-value, ‘UpperFilters’.  This name should have a data value associated with it.  This data value should be a string of ‘PartMgr’.  Ensure this exists.  If it does not, add it.
  • Now in REGEDIT, navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PartMgr    This key should have a ‘Enum’ subkey.  Click on the ‘Enum’ subkey.  In the right-hand pane, you should see a list of every drive you have located in the machine.  If you do not see all of your drives, you now know why things broke down and the driver started to fail at boot.  When I first accessed this key, all that was present was the main root key, ‘Root\LEGACY_PARTMGR\0000′.
  • If the ‘Enum’ key appears to not match what drives you know you have in the machine or is empty, it’s time to have Windows re-enumerate all of the drives in the machine.
  • To re-enumerate the drives is easy…Simply delete the ‘Enum’ key located under ‘PartMgr’ and reboot.  When the machine reboots, it will re-enumerate all of your drives and add them back to PartMgr’s service key.  When this is done, the driver will now know what hardware its controlling and it should start and begin doing its job correctly again.

So, that’s all there is to it.  It took a while of digging and referencing other “running” machines to understand what the problem was, but in the end, as you can see, the fix is incredibly easy.  After I corrected things, the random issues I was having with Explorer locking up and permanently hourglassing when trying to delete and/or rename files went away.  Boot times decreased.  And, overall things seemed much better with the health of the machine.  Of what research I did, I saw that many people seemed to experience this when installing Intel’s Application Accelerator on hardware that didn’t necessarily support the installation of the software (Nice install Intel!).

Anyway. . . hope this helps some of you out there that might come across the issue.

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2 Comments

  1. Spock November 11, 2010 at 8:08 pm #

    It worked!

    Thanks for that.

    Hey, it sounds like you’re a kindred spirit. I started with computers tinkering with Apple II’s in high school, inventing an IBM to apple joystick interface. My first ‘PC’ was a trusty Texas Instruments 99-4/A. Boy, the sleepless nights working in Basic, and the endless typing of program lines. And remember the audio cassette drives for the early machines. What a blast.

    I’m kinda proud to have been around in those times. The genesis of home computing.

    Anyway, cheers.

  2. DogRox April 20, 2014 at 6:43 am #

    Does NOT work for me.. when i add the UPPERFILTERS key to the registry the system locks up when i reboot. I CAN NOT even go in to safe mode.. I have to revert to an BACKUP ghost image.everytime. I use WINXP HOME EDITION SP3 Does anyone know WHY my system can NOT boot when adding that particular registery edit?

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