1TB Seagate HDD missing on Win7 64bit, OK on win7 32bit

[auramancer]

So this internal secondary HDD started disappearing on winexplorer. Usually a reset makes it come back until recently it just wont come up anymore. I'm on dual OS (win7 pro 32bit and win7 ulti 64bit) for work and play separation preference. I replaced the SATA cable and it went back on my win7 pro and the self-dismounting habit is gone. Loading the other OS, the drive initially appeared in the explorer but when its driver software started installing, it just made the disappearing act and wont appear anymore, just as long as I'm on Win7 ulti 64 bit.

So I went back to the other OS(32bit) and it was there, I run HDD tests and it passed, had Steam access it and it didn't dismount. Tried scanning for hardware changes on the 64 bit OS, checked on resource monitor for disks, drive never appears.

Any idea why it behaves as so? And how to make it work on the win7 64 bit?
Here's my system specs for further analysis:

CPU: intel i5 2500k 2nd gen
GPU: GTX550 ti
motherboard: ASUS P8P67

**I know she's oldschool, she a homebrew and still waltzes like a lady**

Please help. Some of my Steam games require 64 bit Windows and I am currently a sad stuck gamer.

 

[samuria]

What does it show in diskmangment?