All credit to J W Stuart
"How to repair and reboot to Windows 7:
a) Insert the Windows 7 System Repair DVD or Installation DVD and reboot.
b) Select the correct keyboard input method and click 'Next'.
Note: If you are using the Windows7 Install DVD then at the 'Install Now' prompt (Do not pick the Install Now option) instead choose the 'Repair your computer' option located in the lower left of the display.
c) The System Repair tool will search for a valid operating system and will report that "Windows found problems with your computer's startup options. Do you want to apply repairs and restart your computer?"
d) Click 'Repair and restart' and reboot again to the Windows 7 System Repair environment.
e) Click 'Next' at the keyboard selection prompt and when the 'System Recovery Options' screen appears verify that the "Use recovery tools that can help fix problems starting Windows" is selected.
f) Now from the menu list select the 'Command Prompt' option.
g) At the DOS prompt type the following three commands:
bootrec.exe /fixboot (may return an 'Eliment not found' message)
h) Close the command prompt window and click the 'Startup Repair' option.
i) The repair process may take some time, so wait until the process completes at which point you will see two messages "Windows cannot repair this computer automatically" and "Startup Repair cannot repair this computer automatically".
Please perform step j as detailed, startup repair must be run multiple times
J) Close this message window by clicking on the X in the upper right corner of the Send/Don't send window. Next click on the 'View advanced options for system recovery and support' option and from the main menu once again click 'Startup Repair'. This time the repair process may only that a few seconds and when prompted "Startup Repair could not detect a problem", click 'Finish' and run the 'Startup Repair' option one more time, click 'Finish', and then remove the System Repair DVD and click 'Restart'. Reboot the computer."