Windows 7: Second SATA HD hangs win7

Hope the title is good enough
Following Kari's excellent tutorial I successfully transferred my WIN 7 and Programs (they are on an OCZ SATA SSD) to a new motherboard and CPU. Until here no problem, the OS started perfectly, went online and activated my copy of Windows 7.
Then I shut down and connected my second HD, a small 320 GB Scorpio where I save all my personal files. Reboot and Windows 7 after loading, freezes. Had to reset and boot in save mode but no information about the problem. devices are OK, the disk is seen from the system with its correct letter but when I boot normally it still freezes the OS. As soon as I disconnect the SATA HD's cable, Windows 7 boot perfectly.
On UEFI Bios all the 6 SATA channels are enabled, I also tried to change connectors but the problem is still there. If additional details are needed, I will be very grateful for some help.

Two questions for you, did you install the chipset drivers for your motherboard, in bios did you set it to ahci mode. Just a couple things to try.

Sigh... yes I did. In fact the firs HD(the SSD with OS and programs) works perfectly and I'm writing form the same PC. The one hanging the OS is the Scorpio if and when I connect it on the motherboard (Asus M5A97 R2.0) whcu has 6 SATA connectors under AMD's south bridge SB 950. At present I attached the HD to an external USB dockstation just in order to access my files.

I'll have to think about this, because i have a SSD with OS and have 4 SATA hdd's hooked up with no problems, so i'm tying to think of a reason why your's is not working, you did set it in bios to ahci mode for the SSD

Another question. Before moving the OS to your SSD was it installed on the 320 GB Scorpio HDD?

I had the same exact configuration before changing mobo. Both, SSD and HD worked perfectly. SSD is working, HD isn't.

My OS was NOT moved; it was and remained on the SSD. The only change in hardware was to assemble a new mobo and using the old disks (SSD and HD). I used Kari's tutorial on this same forum about transferring Windows 7 installation on new hardware. It worked perfectly, since the OS is working (I'm writing from that PC). The problem is the HD which ONLY contains files.
I assume that the HD should be set as AHCI, isn't it?

Sounds like you did it right, but the new motherboard has to have new drivers added ie chipset drivers in order to ensure all functions of the motherboard. Without the chipset drivers the other SATA port won't work.

After 4 or 5 reset, open in safe mode, where I could see that the HD was seen on bios, on device manager, on administration tools and so on, but booting normally would hang the machine, finally I turned off and went for dinner and for a TV movie. Half an hour ago I turned the PC on and to my big surprise, booted normally with the HD at its place!!!! Well, the problem is solved with a little mistery, which is normal in informatics

Sometime's a break in the action works like magic, glad you got it fixed come back and see us when and if you have another problem.