Windows 7 cross-activation problem on 2 PCs

Cut the story short, how can I de-activate the license from a PC?

The full story:
After upgrading an HP dv6-1244XT notebook from pre-installed Vista Home Premium 32-bit to Windows 7 Home Premium 32-bit (provided by HP through the upgrade program), I checked that the installed Windows 7 on the HP notebook had been activated (Start > type and select "activate windows "). It was already a month ago.

But there were some issues that HP could not resolved. So, I tried to investigate the problem. I used the HP provided Windows 7 DVD disc to install Windows 7 on another notebook (but this time I un-checked the "automatic activation" during installation.) But after the installation, I found that the Windows 7 was activated on the test notebooke. (Looks to be loophole).

But on the next day, the HP notebook prompted me for activation AGAIN. I entered the same product key but not accepted. Windows 7 prompted me with a few options including enter a new product key, or contact Microsoft. I clicked contact Microsoft but it became HP Customer Assistant screen that could not detact my Internet connection. So I got no help from Microsoft nor HP on this issue.

I think I need to de-activate the license on the test notebook, and try to re-enter the license key on the HP notebook.

Any advice?

 

Arie, that's my plan on coming Monday if nothing could be done over the weekend.