Did you go to the support page and ask your questions?
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"What do you need to know?"
More than you gave, obviously...
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Ok, this is a Mac forum. < First thing you should know in case you didn't.
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In case you don't care, continue:
1. Computer <What kind of computer>
2. Ram? <How much Ram>
3. OS <What Operating System> 2000, XP, NT
4. Service Pack 2? <Are you up to date>
5. What version of iTunes? 4.9, 5.0, 5.0.1?
6. What is a 3 day restore? You stepped back your OS? Why?
7. How many times did you uninstall? Did you uninstall it completely? You sure? Positive?
8. What version did you reinstall? You sure? Positive?
9. What is not working? What is it doing? What is it NOT doing?
Again, we can't read minds here...