Check your hardware carefully. You may have a loose connection causing the reboots.
Your OD or HD may be failing. You can test this by using another HD and flash stick install writing the ISO to flash stick using Universal USB Installer
with Windows 7 in the dropdown menu, boot under USB, Removable, or HD's. Physically remove the OD first.
Unplug all other HD's and peripherals.
Reset the CMOS to optimal defaults. While in BIOS setup set the SATA controller to AHCI to try install.
Remove all but 2gb RAM to try install. Swap your RAM sticks. Test your RAM: RAM - Test with Memtest86+
Test your HD with maker's HD Diagnostic extended CD scan.