Rest easy! It's not you or your computer. The 2008 rates aren't out yet so the site will send to you "alternate discovery" and right back to 2007 dates.
I have been talking to Disney reservation nearly every day since June 13, 2007. The most recent information I received was that the 2008 rates should be out in a couple of weeks. This was two days ago.
There have been a couple of thread stating that they were told the rates would be out on August 5th.
You can go ahead and book a room only reservation at 2007 rates and then change it over to a package when the 2008 rates come out. If you want to keep it a room only reservation, they will simply adjust your reservation to the 2008 rates.