Unknown error occurred (-42408)

I keep getting "An unknown error occurred (-42408)" when I launch iTunes and it won't sync my iPhone it just keeps saying "Waiting to sync" and eventually it gives me the same error and says the iPhone cannot sync.. Even when no device is plugged in to the computer, that error always shows up when I open iTunes. I don't know why it started happening all of the sudden but I read on the Apple support page that I need to deauthorize then authorize again so I signed into my account on iTunes Store and deathauorized all computers and opened iTunes again and still the same error comes up and it won't let me authorize anymore, same error keeps coming up. I tried everything possible.

I deleted iTunes the right way then downgraded to iTunes 10.5.2 and stll no luck. I even restored my mac and once I updated my iTunes to 10.6 it gave me the same error again. I'm confused because I even restored my mac and that error keeps coming up? I'm on 10.5.8 Leopard so that shouldn't be an issue with that version of iTunes.

Does anyone know what the problem is?