Hi,

 

Follow these steps and check if it helps

 

a) Insert the Windows Vista 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 Vista 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.
Note that on your Dual Boot system there now should be only one operating system listed. Click the ‘Next’ button.
f) Now from the menu list select the ‘Command Prompt’ option.
g) At the DOS prompt type the following three commands:
bootrec.exe  /fixmbr
bootrec.exe  /fixboot (may return an 'Eliment not found' message)
bootrec.exe  /RebuildBcd
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

 

Refer these articles for more information:

 

 

How to use the Bootrec.exe tool in the Windows Recovery Environment to troubleshoot and repair startup issues in Windows
http://support.microsoft.com/kb/927392/en-us