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Windows 7: Dell Inspiron won't start. Missing operating system error

08 Aug 2012   #1

Windows 7 Ultimate x64
Dell Inspiron won't start. Missing operating system error

I have a Dell Inspiron that won't start. It says it is missing its operating system.

Using the Windows 7 DVD that came with the machine I went through the repair Windows procedure 3 times. The first time it searched for restore points of which there are none because the machine has Rollback Rx installed instead. It then restarted with no change. I went through the same process but this time it said it had repaired Windows however; restarting gave me the same missing OS message. On the 3rd attempt it displayed the restored OS as being on D:\. I ran the diagnostic tool and it said no errors were found. Restarting gave the same error.

How can I get the machine to boot from D:\ or move the OS back to C:\ please?

My System SpecsSystem Spec
08 Aug 2012   #2

Windows 7 Home Premium 64 bit

How did that happened? Did you format your hard drive or something? How many drives do you have maybe its installed on another one.

If all else fails the only thing left to do is to do a system recovery or factory restore, if you are looking for a clean start then follow this guide: Clean Reinstall - Factory OEM Windows 7
My System SpecsSystem Spec
08 Aug 2012   #3

Windows 10 Pro X64

Can't you use Rollback Rx to resolve the problem? That's what it says it's for, "even if you can't start windows".
My System SpecsSystem Spec

08 Aug 2012   #4
Microsoft MVP

Windows 7 Ultimate X64 SP1

In addition check your BIOS boot priority settings, make sure the OS drive is before other other drive.
My System SpecsSystem Spec
09 Aug 2012   #5
Microsoft MVP


Ignore the drive letter assignments in Repair Mode which are often different than from the desktop.

Work through these steps for Troubleshooting Windows 7 Failure to Boot.

It often won't even begin to repair until it is disinfected. Then every step to get it started is included, and how to rescue your files to run Recovery or Clean Reinstall if necessary.
My System SpecsSystem Spec
09 Aug 2012   #6

Windows 7 Ultimate x64

This is not one of my machines. A friend brought it to me saying he had been having intermittent trouble starting it over the previous 2 days and that now he couldn't start it at all.

I asked him if he had tried Rollback to solve the problem an his response was affirmative, he had rolled back to the previous day and that started the machine but now it didn't want to know. Asking when exactly the problem began, I suggested we rollback to the date prior to the problem's appearance but the result was still "Missing Operating System".

Reading on this forum that it can sometimes take up to 3 repairs and reboots, I ran the sequence of repairs (FixMbr, fixboot, etc.) and it now boots into Windows again. I would love to say the problem is resolved however; we now have a new set of issues which are exacerbated by the fact that my friend became complacent and stopped backing up his data on a regular basis. The system appears to have removed Rollback Rx so there is no way to get back to a later image or recover data from one. It also appears to have returned to the original baseline installation meaning he has lost all programs and data. Even his Comodo internet security suite and Malwarebytes are missing!

I'm thinking that maybe the best solution would be to do a fresh Windows reinstall because whatever the cause of all this nonsense was may still be present.
My System SpecsSystem Spec
09 Aug 2012   #7
Microsoft MVP


You mention some apps which have been problematic in the past. Comodo firewall causes persistent problems. I would uninstall it and use ONLY the apps we recommend to setup and maintain a perfect Clean Reinstall - Factory OEM Windows 7.

In addition the Win7 System Restore works fine and if disk space is available can be configured to reserved up to 20% of the HD for more points which last longer: System Protection - Change Disk Space Usage. Using some third party restore/rollback program could also cause problems such as what you mention which never otherwise happens unless you have a virus which hides files, or have somehow run Factory Recovery.

We have been with the OS since before its release and now know well the Best Practices for installing and maintaining it flawlessly. So if you want to try fixing it hew to Troubleshooting Windows 7 Failure to Boot or if it will boot Troubleshooting Steps for Windows 7. If you run Recovery then Clean Up Factory Bloatware. Or best of all get the superior Clean Reinstall - Factory OEM Windows 7 done correctly the first time so that a Win7 backup image can be relied upon for any future reinstalls.
My System SpecsSystem Spec

 Dell Inspiron won't start. Missing operating system error

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