One day you wake up and start your Windows 7 PC, and to your surprise you find a horrifying black screen saying “BOOTMGR is compressed Press CTRL+ALT+DEL to restart ” as shown below, and even if you try to restart it, Windows will never start. This is a very simple problem. It usually happen when your computer is not shutdown properly, may be due to power problems, or when you or any of your users mess with the Primary dive (normally your C drive). Due to any of these reasons, your system finds that the primary drive where the BOOT MANAGER(BOOTMGR) resides is compressed. You just need to un-compress it or at least tell your system that it is not compressed.
You will need your Windows 7 or Vista Installation disk or pen drive to solve this problem. Just follow the detaild steps given below.
Boot up your computer from the Windows Setup Disk or Pen drive. You need to boot from the correct device or location to start the setup. Once started, Click on Next.
In the nest screen, click on Repair your computer.
Now go to my Computer. and then select your Primary drive (Normally C drive). Right click on the drive and select Properties.
Now in the properties, you will possibly see the Compress this drive option Checked. If it was Checked, uncheck it and clock on Apply. If it was already unchecked then Check it and Uncheck it and the click Apply.
After applying the new Compress status, it will ask if you want to apply the changes to all subfolders and files. Yes, uncompress all the subfolders and files. Click OK. Please note that this process may take some time depending upon the amount of data available in the Primary drive.
After the process is completed, you can simply cancel the setup. And then restart your computer. If everything goes right, the Windows should start.
I hope your problem has been resolved.