having trouble downloading disc 2 of forza 3

[SLIK4]

i'm not sure what to do. for forza 2 all i had to do was put the disc in select what i wanted and it downloaded and i was ready to rock. but when i try for forza 3 when i put the disc in it simply tells me to insert disc 1 so i do...still nothing...when i go to the place where it says install disc 2...all it tells me to do is to install disc 2 and let it download except it won't download. i even tried copying disc 2 to my hard drive and still nothing.

thanks in advance
Michael (xbox gmrtag = shrpshootr4)