Ok so I had an application that needed Windows 7 install to use it. I did not want to use my current Hard Drive (Toshiba 1TB 7200 RPM, also has Windows 8.1 X64) to dual boot. So i took an old laptop hard drive (WD Scorpio 80 GB 5400 RPM) and put it inside my computer with another Sata connector (currently on Sata port 2) and installed Windows 7 Pro X64 on it. Now as of last week i found a different program that replaced the old one (it works on Windows 8.1 X64). I wanted to take the other HDD (WD Scorpio) out of my computer. But now when i boot up with out that HDD in my computer i cannot boot to my original HDD (Toshiba 1TB) without the WD Scorpio in my computer. Is there any way to fix this? I only want to reinstall Windows 8.1 if i need to. i just want to have my Toshiba HDD be the main HDD and be able to boot in to Win 8.1.