Do you use aptitude?
I usually use synaptic. At the beginning I also used update-manager, but I left it because it is not very functional.
In text mode, I used to use aptitude as I was taught this way. Now I use apt-get. Always after installing/upgrading, I used to open a console and run aptitude clean (there is no way to clean the cache in GUI, is there?).
I do not remember having used aptitude for anything besides cleaning the cache up, but I am not sure at all about this point. Sorry.
Please provide your dpkg log(s).
I am afraid it is impossible. This computer is at work, it does not belong to me, and I cannot compromise the privacy this way. I cannot post them in the bug, and neither can I send them privately to you. I am very sorry about that.