I just ran into this on a new batch of Latitude E6420 latpops. I tried another suggestion in a forum post to rebuild the KBE, as well as other things (power cycling K2000, reseating laptop's memory), but continued getting the error when the KBE was attempting to load:
Not enough memory to load specified image
This was true even with the default x64 KBE that comes with the K2000.
The issue turned out to be due to the BIOS version (A13) - downgrading to earlier versions (A08, A12) resolved the issue and my scripted installs are running fine now. I believe engineering will look into this, but for anyone else in the same boat this should get things working again.