Unplug any devices attached.
Try tapping the F8 key at bootup, see if Repair console is on Tools Menu. If so, access it to run Startup Repair which should automate System Restore. If not, run it from list.
If you cannot boot the Windows 7 DVD to access Repair console, or even the F8 tools menu, then you have hardware problems.
Try tapping the key given to enter BIOS setup to reset the CMOS: Clear CMOS - 3 Ways to Clear the CMOS - Reset BIOS
If you can't access the BIOS then you may have a mobo problem. Try pulling the CMOS battery as shown in tutorial.
Test your RAM with memtest86 CD which will autostart for 5-6 passes: RAM - Test with Memtest86+
Test your HD using maker's diagnostic/repair CD extended scan: HD Diagnostic