CPU busy (again)

Haia I noticed this morning on my SUSE 9.0 box that the CPU was busy ( around 40 to 50%) even when no program was running. I used >>TOP>> to check and System Monitor but there was no indication that a program was occupying the CPU. Is there another way to find out what is using the CPU? Two things I have done in the last days: I upgraded the kernel with the patch on "YOU". I printed some photo's on my HP2110 printer. Not sure if this is of any help but I put it here anyway. Can anybody suggest what to do? TIA. -- Greetings from /bill at 169 west , 19 south. Disclaimer: Any errors in spelling, tact, or fact are transmission errors."