Ive had the samsung galaxy tab for 2 months and today when i turn it on instead of the normal log in theres a white box with a mini android man and a large android man the large one is flashing green and has downloading underneath it !. logical thought its down loading ! but its been downloading now for 2 hours and all other functions are blocked the on /off does not work ,nothing works !! has anybody else had this and if so how long does this "download "take ??