Okay, I've been running my head into a wall over this for a while, so I've stripped it down to the bare minimum and decided to reach out for a bit of help. Details of the problems are in the headers of the two links posted here:
http://pastebin.ca/1542247
http://pastebin.ca/1542243

The first one is working as expected, but the second one isn't. What I would like to know is why

UPDATE: It seems that it only fails to function on SMP systems. If forced to run with only one processor (ie: taskset -c0), then it behaves. Problems seems to exist with QApplication as well, so I've changed the topic to PyQt question since it's certainly no problem of KDE/PyKDE/KApplication. I would still love very much to know what's going on though!!

UPDATE: It seems it's just bad code, and it's a wonder that any of it worked at all. Here is the solution that I've decided upon thanks to a bit of friendly advice in #qt: http://pastebin.ca/1542738