Windows 7 Professional, Startup Repair use

Have you ever wondered what exactly is done when a start repair runs in Windows 7 boot process?
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Here's a quick, yet informative, blurb from Microsoft TechNet.

Manual Diagnosis and Repair:

When starting from a Windows using the F8 advanced boot option menu to launch the on-disk Windows RE, the user can manually launch these system-recovery tools:
-Startup Repair (when not launched automatically)
-System Restore (on rollback, by using existing restore points)
-Complete PC Restore (to restore from a volume backup image)
-Command prompt, from which all standard Windows PE console tools, such as Regedit and ChkDsk, are available
-Custom support and recovery tool included by computer manufacturers

Startup Repair
Startup Repair is a tool that automates common diagnostic and repair tasks of unbootable Windows 7 installations. If the computer fails over into Windows RE because of a detected boot failure, Startup Repair launches automatically. If automatic failover to an on-disk Windows RE is not available, Startup Repair can also be launched as a manual recovery tool from a Windows RE CD/DVD.

Startup Repair Process
Startup Repair will try to repair computers that are unbootable because of the following reasons:
-Registry corruption
-Missing or damaged system and driver files
-Disk metadata corruption (MBR, partition table, and boot sector)
-File system metadata corruption
-Installation of problematic or incompatible drivers
-Installation of incompatible Windows service packs and patches
-Corrupt boot configuration data
-Bad memory and hard disk hardware (detection only)

Startup Repair will not repair unbootable systems caused by the following issues:
-Malfunctioning firmware and other hardware components
-Problems with clean Windows installations or Windows upgrades (for example, from Windows XP to Windows Vista)
-Windows logon errors
-Viruses and malicious software

Startup Repair Log
After Startup Repair has run, a text log with diagnostic information and repair results is generated. This log file is located at %WINDIR%\System32\LogFiles\Srt\SrtTrail.txt.
The log file begins with information about the diagnostic and repair session.

An example and this information can be found from this Microsoft TechNet posting.