When I bought my itrip auto and plugged it into me car charger for the first time my I pod froze, as you can imagine I panicked and thought that was the end of it however after a quick visit to the manufacturers website my mind was eased.
Here is the explanation of how to perform a soft reset on your ipod if it freezes when you first plug it in.
if you hear the static on your radio go away when you turn on the itrip auto and your ipod is getting power from the itrip then all you need to do is a simple soft reset of your ipod.
With the itrip connected to the ipod and plugged into the lighter socket, hold down the menu button and the centre selection button at the same time until the apple logo appears, release the buttons and wait, the ipod takes a short time to re boot. the ipod will restart and should now communicate with the itrip successfully.
Hope this information helps. I am over the moon with mine, no more messy cds rattling about all over the car floor.