Windows does not boot after compressing System Drive

We have seen how we can compress files, folders or even drives to save some disk space. To many compressing the System Drive or the C drive to save some more space may look tempting. But this can create problems!

Compressed System Drive – Windows will not boot

Using the Compress feature on the system drive can compress some of the files required to boot the Windows OS. This could simply make your Windows computer NOT boot! You could even end up with a boot-loop!

In this article, I’ll show you what you can do if your Windows computer fails to boot or goes into a boot-loop after compressing the system drive OS drive.

There are a couple of methods we can try. I’ll list all of them you can find the best method that works for you.

Run Startup Repair

The first method is to run the Startup Repair. It may or may not work, but it’s the easiest method to try. Run the Startup Repair, three different times. Because sometimes it sometimes takes three runs to fix it. If this does not fix your problem move on to the next option.

Manually uncompress the files

The next method is to manually uncompress the files of the Windows installation drive. Follow these steps:

  • Insert the Windows installation disc or USB flash drive, or a system repair disc, and then shut down your computer.
  • Then restart your Computer
  • When prompted, press any key, and then follow the instructions that appear
  • On the Install Windows page, or on the System Recovery Options page, choose your language and other preferences, and then click Next.

1 400x300 Fix: Unable to boot the System with error code 0x490, with Windows Startup Repair

  • Click Repair your computer.
  • Select the Windows installation you want to repair, and then click Next.

2 400x308 Fix: Unable to boot the System with error code 0x490, with Windows Startup Repair

  • Now click on “Load Drivers.”
  • You’ll get this screen. Click OK.


  • Now you’ll get an explorer window. Click on Computer


  • Right-click on Installation Drive which would be the C drive in most cases. Select Properties.


  • Uncheck on “Compress this drive to save disk space” and click Apply/OK.


  • Make sure it says “uncompress” and ensure that “Apply changes to drive C:\, subfolders and files” is selected.
  • Now click “OK” and wait for few minutes until it uncompresses.
  • Once it’s done reboot your computer normally and see if it loads.

This should work. If it does – great! If not, you have just one last chance!

Manually rebuild the MBR

The last method is to manually rebuild the MBR or Master Boot Record. There are a lot of ways to do that. You can follow this video tutorial created by me on how to Rebuild MBR. For details on this, check this tutorial on how to fix the Bootmgr is Missing issue.

Hope something helps! If none of the steps work, then feel free to post it in our forums. We’ll be glad to assist you there.

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Posted by on , in Category Windows with Tags
Shyam aka “Captain Jack” is a Microsoft MVP alumnus and a Windows Enthusiast with an interest in Advanced Windows troubleshooting. Suggestions made and opinions expressed by him here are his personal one's and not of his current employers. He blogs at


  1. ntm91307

    This one fixed my problem. Thank you very much…:)

  2. Chief Keef

    It solved my problem. Thank you very much 🙂

  3. Abdoulaye Ouedraogo

    Since I compressed my disk, my sreen displays “IWTLR is compressed … press ctrl+alt+del to restart” . But still pressing those buttons doesn’t change anything.
    Please do advice
    By the way, I use windows 7
    Thanks in advance

  4. IWTLR is probably your bootcode or the name that was given by win7 to your bootdrive. Try booting from your install disc, start recovery, at the first screen select “load drivers”, and then you should see drive “C:” , or it might appear as “system reserved”. Click on that drive. Then at the bottom of the window, DESELECT “compress this drive to save disk space”. Click ok, finish, and reboot.
    Compressing a small partition of 100 MB doesn’t really make sense anyway, it’s a bug in the compression algorithm of Win7/8, it should have skipped that partition automatically.

    READ the post – here on this page – because it tells you EXACTLY this, in detail.

    You will probably have to wait a few minutes for the decompression.

    Let me know if this helped you.

  5. Abdoulaye Ouedraogo

    Thanks a lot dear Attila Szabo . I shall do what you advised an keep you posted on the outcome.
    Nice day

  6. No problem. If it doesn’t help you, we’ll figure something out to help you anyway. The technological possibilities are here, we just need to use them 🙂

  7. riza cruz

    I don’t know what happen to my laptop. But before I can use it tho it always prompt “Start up repair” and below it “Click windows to start normally.” But suddenly i can’t open it to windows normally. I thought it was due to virus or something. but I’m not really sure about it. But when we tried to have it check they say that the hard disk need to be change. Is there other options to fix it? Please help me. I really need your help. Thanks in advance. 🙂

  8. Run Startup Repair 3 times using the Windows 7 disk.

  9. István Jakab

    Your instructions were of assistance, the problem is solved, thank you very much!

  10. Which one of the solutions presented on this page helped you ?

  11. Tommy Hoang

    My laptop says, “CVFN is Compressed press ctrl+alt+del to restart your computer” I’ve tried using the install disk, but it won’t pull up through the disk either. It stays on the same black booting screen with the _

  12. Lalit

    Yes, this really help

  13. ryan

    I have done uncompressing but now im stuck with starting up with windows logo then it automatically restarts to windows error repair

  14. Nishtha

    I dont have microsoft installation cd, is there any other way of making it work?

  15. Joy Reina

    Sir good day i have a problem from my pc stked is compressed appear pls! Help what i will do.thank you.

  16. juan

    An excellent explanation, problem fix it !!!!!! an AAA+++

  17. ????????????? ???????

    I have to say big thanks!!! You saved my day
    Very appreciated of the detail provided by the blogger
    This is a very very helpful information. Thumbs up!

  18. Gift Chelraj

    It worked! Thanks for your help.

  19. Aivan Karlo Geronimo

    I have this problem too, but mine is SLAXC is compressed, press alt+ctrl+del to restart. But I cant enter my BIOS settings idk what to do anymore. Please help

  20. Aivan Karlo Geronimo

    nvm my post. I already fix it. i just removed my CMOS and i can enter my BIOS again, then after that i inserted the Windows disc and started the repair. thanks

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