Dubya was like a monkey taking apart a Corvette engine. He tore everything apart thinking he could make something run on nothing. He threw out the timing gears, ground off some cam lobes, lost 4 fuel injectors, used lard to lube the bearings, left the piston rings out, replaced the engine computer with an ipod, dropped the flywheel on his foot, and left the parts out in the rain for the next guy.
When you completely destroy something like Dubya did, it takes a LOT of money and time to fix it. Obama can't fix this mess over night.