How to debug a CPU hog?

[Zuxy Meng]

Hi all,

My pidgin hogs an entire CPU core (resource manager shows about 50% CPU 
usage as mine is a dual core) after several minutes, even after I've 
disabled all my accounts and plugins. I'm using pidgin 2.6.3 (the problem 
has been there for quite some time so it isn't a regression of the latest 
version) under Windows Vista SP1 32-bit.

Can anybody give me a hint as how to debug the problem? How can I find which 
function is the culprit? I have a working MinGW gdb installation.

Zuxy