Thanks Cris - that's a perfect sample you've given me, and that is one weird stack in the sample!
Alas am up walls with real work at the moment (it's past midnight and I'm still working!) so will get on to this at the weekend.
Presumably after you killed it, all was well again?
You might also try updating to 2.4.7 beta ... the copyrights line in the prefpane is up-to-date