[CentOS] High CPU usage for migration kernel process

I've got a CentOS 4.3 box here which is exhibiting crazy (I think)  
CPU load on one of the four migration kernel processes:

# ps ax | grep migration
     2 ?        S      0:08 [migration/0]
     4 ?        S    112:23 [migration/1]
     6 ?        S      2:48 [migration/2]
     8 ?        S      0:11 [migration/3]

It's running kernel 2.6.9-34.ELsmp.

Does anyone have any idea what might cause that?

Thanks :)

-- 
Andy Armstrong, hexten.net