Problems with the stick
Sources inside the development of the Ares 1 launch vehicle (aka Crew Launch Vehicle or "The Stick") have reported that the current design is underpowered to the tune of a metric ton or more. As currently designed, Ares 1 would not be able to put the present Orion spacecraft design (Crew Exploration Vehicle) into the orbit NASA desires for missions to the ISS. This issue is more pronounced for CEV missions to the moon.
Bummer but I would think this isn't as bad as if there was a problem with the eventual Ares 5 HLLV. Aren't there existing launch vehicles that can lift the CEV? TB should know this...