Hi
Hi I hope you have a 64 bit Windows 7
(exact match to Home, pro or enterprise is not so important)
Did you go through the fix startup options as well as chkdsk ?
You need to record exact error messages and what program generated error message
often Googling error messages finds solution
one is
http://www.tech-recipes.com/rx/2605/fixing_the_dreaded_unmountable_boot_volume_error/
Chkdsk /R C:
when that finishes note any errors
reboot off Windows DVD and run
Chkdsk /R C:
again
(sometimes necessary if lots of file system corruption)
See if you can start in safe mode
(F8 just after bios messages finish, note F8 also used by BIOS in some cases)
best of luck
Mike Barnes