I have an old computer which is very suseptible to applications in the
background hogging up useage. So when using system monitor, I noticed
that the processor useage was 100% even though nothing was running in
the foreground. It turns out that when I run Yahoo Messenger, the
processor useage shoots up to 100% and when i close it, it's still
running at 100% useage.

So what's going on?