iTunes crashes only 1 of my two iphones..

For some reason when i connect my iphone to iTunes, it crashes straight away. I get the beachball, and I have to force quit the app. I am unable to ever get anything synced with my phone, or put new music or videos on it bc of this. However, my fiancees phone is synced with my iTunes as well, and hers pops up instantly. We have the same iTunes account and everything. Same apps. How is hers not crashing it? Or most importantly, what is on mine that is.

Also, we just go the brand new 3GS's two weeks ago. No jailbreak or anything. Only time i was able to connect was the initial plug in out of box. Ever since then, craaaaash.

Any help at all would be great!

Already I have:

Deauthorized computer twice
reinstalled iTunes 5 times (deleting plist files too)
logged out of iTunes store and logged back in
Completely reinstalled Snow Leopard (Figured why not)


Thanks everyone...