You could try booting up into the Advanced Boot options by tapping F8 (usually) as you switch on and select Repair your Computer then navigate to the Recovery Environment and select Startup Repair to see if that comes up with anything - although I've never really seen it achieve anything.
Or, you could create a bootable Paragon Rescue Disk
http://www.paragon-software.com/home/rk-free/This is really for when you can't boot up at all but it does have a Boot Corrector as well as other tools you could let it run through.
Click on the Downloads & Manuals link on the left and you can download a tutorial for it.
You will need to change the Boot order which you can do a one off by usually tapping F12 as you switch on, but when you switch on normally you will see which keys apply to your machine.
It is usually F2 for Set up which is the BIOS and F12 for the Boot order change but look carefully the next time you boot up, although the time it is taking to boot up, you may have plenty of time to read what it gives.
Select ODD (DVD player) insert the disk and press enter.
The disk may boot straight up or you could get a prompt to press any key to boot from CD/DVD
Did the sfc /scannow report that it had repaired all files or just some at the end of its scan ?