I have a problem with my Windows 7, hardware : Acer 3820TG Operating Systems : Windows 7 and Ubuntu 10.04 dual Case: When I try to boot my windows 7 I see an error: "Window failed to start. A recent hardware or software change might be the cause. To fix the problem: 1.Insert.... 2. .... ... status : 0xc000000f info : The boot selection failed because a required device is inaccessible .... " I can't exactly remember what were my last actions on Windows. I already searched this error and applied the proposed solutions, I created a repair USB (because I don't have a CD-ROM nor a Windows 7 CD) such as; -repair operating system :it says it cannot repair it -checking disk (chkdsk D: /f /r) : it checks the disk without a problem or error and it takes pretty long (more than a hour). But when I restart, still the same error. -I didn't create a restore point so I pass this option -I don't have a system image -I tried to run windows recovery (I have a recovery partition) but there are just two options: 1- Format the operating system but retain user data (copies the files under users to c\backup folder, but when I searched deeper I found that there are some people who already tried this option and couldn't find their user files under backup directory). Plus, I have unfortunately just one partition D (it is a fault I know) because I use always Ubuntu. So this is not applicable in my situation 2- Format entire system (Windows). I keep my valuable data in windows but not in user folder. I was reaching them from Windows. -I tried to repair windows boot by: bootrec /fixMBR bootrec /fixBoot bootrec /rebuildBCD I lost all grub menu, and reinstalled it. - ubuntuforums.org/showthread.php?t=1014708&page=29 nothing changed, same error. I created a thread in microsoft forums - http://social.answers.microsoft.com/Forums/en-US/w7install/thread/69517faf-850a-45fd- 8195-6d4ed831f805 but I couldn't find a solution. Before I run chkdsk from usb repair disk I couldn't able to mount Windows (NTFS) partition from Ubuntu, I was getting "couldn't mount file system, error code 2". I tried to fix ntfs partition from ubuntu and got "segmentation fault". I also created a thread on ubuntuforums for this mount problem: - http://ubuntuforums.org/showthread.php?t=1606427 So, after chkdsk, I could enable to mount windows partition but all I see in this partition is chkdsk logs, no any other data. Now, I don't think I lost my data because I don't get any filesystem errors, just the boot section, but this log files under windows partition makes me afraid. I see that Microsoft developers don't have a solution yet for this error. If you need any information to get more idea I can give, maybe I miss some points or it could be complicated. Thanks in advance.