No idea what you mean, really. I installed it once and it never bothered me again. Quicktime on the other hand closes a full-screen application to announce that it really, really wants to become iTunes now.
I love iTunes. It's a great program. One friend of mine installled it and I had to reinstall all the sound drivers for her. The other did it as well, the taskbar stopped displaying windors and after 5 hours of struggle we had to reinstall the whole OS. The best thing about it though, is that you can't just ask you PC to remove it and start working like before. Nope, it'll take 50% of your system files and drivers with you. Great program. Love it.