Windows 7: Secondary HDD disconnecting randomly

For the last couple...well, months really, my 1TB HD has been disconnecting from my computer. I made the mistake of not taking care of the problem the first time it happened and now it disconnects whenever I put even a little bit of stress on it. When it first started happening it seemed like it was getting overheated, but it wasn't hot to the touch. It's currently 95 here in Oregon and I'm not sure if it's a coincidence that the HD is having many more issues.

For starters, I made the mistake of loading all of my movies/music/games/major applications on it to save space on my SSD...so now every time it disconnects my computer is virtually useless.

I can restart my computer and the HD loads and works fine, but if I try to open an application that is installed on the HD, even something as simple as a movie or iTunes it basically lags out my computer and disconnects. I've tried CHKDSK, defragging, and all of the other diagnostic tools that come with Windows but nothing has worked so far and the diagnostic tools don't seem to see any problems. I've also checked the cables and everything is connected and obviously working...for the first few minutes.



If I absolutely have to I can get another HD but nobody wants to go through the pain of reloading over 900gb of stuff onto a new HD.

Any help would be appreciated, and if anyone needs to know more just let me know and I'll do what I can.