After I repartitioned and installed Slackware64 on my laptop, the Windows 7 failed to start. The error status is 0xC0000225 and the error message is "the boot selection failed because a required device is inaccessible". This problem is easy to be fixed as long as you have a Windows 7 Recovery Disk. You just boot your PC/laptop using this disk and follow the instruction for repairing the Windows. After repair is finished, the disk will restart your PC/Laptop, then, you will get back the Windows 7.
Please note that you have to use the same version of recovery disk, I mean, if you have Windows 7 32-bit on your PC/Laptop, you have to use Windows 7 32-bit Recovery Disk, vice versa. You can create your own Recovery Disk from your existing Windows 7. For further information about creating Recovery Disk, please consult to Microsoft website.