Windows 7 not booting on 1.5TB Caviar Green

I recently bought a new Caviar Green 1.5TB HDD, model # WD15EARS. It was working great for about a month until yesterday. Bios detects the hard drive and isn’t reporting any issues. I connected another hard drive with a fresh copy of Windows 7 so I could access and backup files from the 1.5TB hard drive. Problem is when I have the 1.5TB connected, it makes my other hard drive unstable. It becomes so slow and sometimes it just freezes. I try to access the 1.5TB from Windows’ My Computer, but it doesn’t let me. It shows the drive is there, but it won’t let me access anything. I disconnect the 1.5TB and everything goes back to normal.

This is a fairly new hard drive. I doubt it’s defective or dead since I never received any SMART warnings. I have no problems at boot up. My PC just freezes at the Windows 7 loading screen. 

I hope my hard drive isn’t dead. I just backed up everything from my previous dying hard drive onto this one!

Edit: 

Here are couple of photos I took with my camera when doing the diagnostic tests. Sorry for the poor quality. I couldn’t take a screenshot.

Edit # 2:

I was successfully able to transfer files to my backup hard drive using Active@ Boot Disk. I used the GUI features because the DOS prompt couldn’t find the User’s folder in the Windows 7 root directory. Anyway, it seems that transferring files from my 1.5 TB to my spare HDD was pretty quick. Only problem was the Active GUI took forever to load! I don’t think the drive is dead, mechanically. Probably some of the electronics on the drive are malfunctioning?  It seems the 1.5 TB is hindering the performance of the CPU and/or RAM. This would explain why the other operating systems on my other drives were performing very slow. 

Edit # 3:

FIXED! :smiley:

My hard drive issue has been fixed! All it took was a five hour DLGDIAG Diagnostics extended scan. It seemed to have repaired the problem. My computer is running at normal speeds again with no hiccups at all.

My only issue right now is with the  Data Lifeguard Diagnostic for DOS (CD). Every time I try to boot into DOS with it, I would get an error “Unable to locate the License Agreement file, DLGLICE.TXT!!! Please make sure that the License Agreement file is located in the same path as DLGDIAG.EXE.” I see that someone else is having the same issue here, too. My workaround was to download Hiren’s BootCD because it has the latest LifeGuard Tools.

Also, for the DLGDIAG for Windows, the SMART status for my hard drive is displayed as N/A. I can see the status for my other Hitachi drive, though. I have SMART enabled for this drive and I’m also able to see the SMART status using other hard drive diagnostic software.