100% cpu usage when I (admin) am online

Hi there...

For some time I've run my server with bukkit now but a strange thing happened to me today.
I use build 531 and run my server on a CentOs 5.5 VPS server.

I was happily playing minecraft today and suddenly it started laggin like hell. I went to investigate and discovered that the java process uses >100% cpu (top reported 110-150%).
Strangely, this happens ONLY when I try to connect.
If one other player connects, cpu usage goes from ~10% (idle) to ~15%, if I connect, regardless of other players, cpu usage spikes to max.
I also disabled all plugins and this still happens.... :S

Does anybody have an idea?
I did not change anything on my server (it worked, then this happened)...
I even restarted the server with no effect.

thanks
tyderion

Edit: bukkit version wrong xD

 

I get the same.
My CPU usage has jumped alot higher than it used to.
Plus when i connect to my server, it's unplayable.