First, I'd say ditch app killers...they do more harm than good. Second, I haven't used an IM app for awhile, but when I did, trillian seemed to work pretty well. All the apps you mentioned (including trillian) have their quirks, but I'd suggest getting rid of your app killer first and then trying those apps again and seeing which one works the best for you. From my experience in the past, I had the best luck with trillian and IM+.
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