VERY strange Kernel_task behaviour

Hi guys,
I recently moved to a Macbook running Leopard (10.5.4) and had this very weird behavior a couple of times, without being able to reproduce it.
It happened that after using Itunes for some time, say 1 hour, the kernel_task was going mad, picking from -880 to 3,2400 (yes, I'm serious), with all other processes behaving as normal. I shut down every running program, but this didn't affect anything. At the end, I discovered that unplugging the headphones would bring everything to normal, and plugging it again would trigger the bizarre behaviour of kernel_task. I've checked Console messages, but nothing relevant there. The weirdest fact is that after a while, say 30 min., everything was ok again. I'm now trying to run Itunes again, and see what happens. I kinda suspect is something hardware, more than software.
Any idea about it?
Thanks in advance for your help,

Sandro

 

Yes, I tried with two different set of headphones, and with some speakers, but it was the same. The weirdest thing is that I'm not able to reproduce it, but it happened three times in 4 days. Now, for instance, Itunes is playing and everything's fine.

 

Ok, now Itunes finished its list, I minimized it and here's the problem again. Quitting Itunes doesn't change anything.

 

Ok guys, some (weird) news. If I play something in Itunes while the kernel_task is going crazy, it works perfectly. If I hit pause, the problem is there again (with the headphones plugged in). Also, I've open an avi file with VLC, and for the first few seconds there was no audio, then audio came back, and the kernel_task went down to normal levels.
Can it be a bug with the audio management in Leopard?