Core2Duo utilizing only 1 Core?

My system seems to not use both cores of my Core2Duo Processor...

1. HWMonitor shows only one Core.

2. A gadjet that monitors CPU activity, when I forced a cpu load (registry search) Core1 reached 100% but core2 was not used at all.

3. In my Device Manager I see 2 cores.

4. Taskman shows only one activity window for one core!

Any thoughts? Anyone else noticed that on their system?

I haven't installed anything except for Windows Update-found drivers
Motherboard: ASUS P5LD2X/1333. No chipset drivers manually downloaded. ( I will test it after downloading them, but it's strange how it is now)

Note: I have another PC with ASUS P5GC-MX/1333 and it shows both cores...

I'm posting from my other PC....

I have 2 cores checked by default in msconfig, that's the first thing I do after an install, but it has to do with how many cores it uses during boot only, not later use in the system.

I checked "DETECT HAL" , and now my PC starts with a black screen only.
I can only see the watermark "For testing purposes only" but not anything else. Dead. Mouse and all respond, but I'm actually locked out. I'll enter repair mode to change bcdedit to "detecthal no" if I can access it and post back. This didn't fix it Locked me out. wtf?

Ok, after doing what I described above, I'm back online.Still 1 core though..

So my PC doesn't want "detecthal" option..why is that?
I'll play around some boot options and post back.

MrGrim, can you give me a reference to what exactly detecthal does? I'll search into it.
Thank you in advance.

No problems, I'm a PC technician, I would find my way out, no worries..

I found this which is your solution:
1 CPU detected in dual core system. -Solution - Vista Forums

Let me try some different boot configs and post back.

Cheers

Yup, that's the correct option.
Sorry or not, you'll get your rep! It worked. It's just that I shouldn't have checked "Number of CPUs". I should have left it unchecked to defaults.

Now it detected my second Core.I can see it utilized.
I'll try now to uncheck it , check 2 cores, and reboot, to see what happens.

Thanks!