I seem to be having the very same problem, bought an 07 LTD brand new lass fall from a dealer. Parked over the winter with a couple of start ups with no problem. I drove it about 2 weeks ago without an issue. Yesterday I went to start it and it was completely dead! I jump started it and drove for about an hour, but tonight tried to fire it up and had the same issue, dead as a doornail. It's still under warrantee with 1900 miles, so I guess I'll jump start it and drive it straight to the local dealer (before they close their doors!).

Car looks great, to bad it won't go anywhere....