Most of the times when the system gets halted improperly due to power outage or due to some other reason, the file system gets corrupted and Windows is unable to mount the boot drive properly. There are other factors that also result in unmountable boot volume. These include faster UDMA modes configured in BIOS and using 40 wire data cable for the hard drive.
- Load the fail-safe defaults in your BIOS and use 80 wire data cable for the hard drive for optimum performance.
- If the file system is demaged (which usually is the case)
- If you have Recovery Console installed at startup, then start the recovery console and go to step 3. (See here how to install recovery console at startup)
- If Recovery Console is not installed at startup, then boot with Windows XP CD.
- When the “Welcome to setup” message appears, press R to start the Recovery Console.
- Select your Windows installation and type administrator password when prompted.
- At the command prompt, type chkdsk /r and then press enter. This will check your file system for errors and try to fix if any.
- When the above process is complete, type fixboot at the command prompt. This will fix the boot sector of the hard drive.
- Type exit at the command prompt to restart the system. Most probably the system will boot into Windows now.