Hello all, Yesterday, my iPad 2 3G gave me the error "Invalid SIM." I turned off the iPad, removed and reseated the SIM, and the problem went away. Later, it gave me the same error. Has anyone had this problem? The only theory I have is that this is because I swapped the SIM from my iPad 1 3G. Although why would it stop now when it has been working in the iPad 2 for 3 weeks now? It even renewed the data plan successfully. I'm also thinking that the iPad 2 may have a problem with the SIM slot. To test this, I put back the SIM that came with the iPad 2. So far, the error hasn't occurred. It could also be that the iPad 1 SIM is has gone bad, although I have never heard of that. Any thoughts? Thanks.