For more information on Windows problems (both solving and creating) I highly recommend reading the following chapters in my book Upgrading and Repairing Windows, 2nd Ed.
- Chap. 2 Windows Boot (Startup)
- Chap. 10 Windows File Systems
- Chap. 11 Windows Data Recovery
- Chap. 12 Windows Troubleshooting
These will give you a good foundation on Windows errors, including those related to startup (e.g. bootmgr) and the file system. Scott.