Have you tried a Startup repair?
If not, boot from the DVD, press any key when asked to. Answer a few questions regarding language, time/currency and keyboard and bottom left is Repair. Select Repair then select the OS to repair. The choices are Startup Repair, System Restore, Backup Restore, Memory Test and Command Prompt.
Firstly, choose Startup Repair.
If it doesn’t work, boot from the DVD again and choose Repair > Command Prompt then type chkdsk /r and press Enter.
If it still doesn’t work, boot from the DVD again and choose Repair > Command Prompt, type sfc /scannow and press Enter.