Cannot boot new Latitude E5520 to KBE
This is my second batch of E5520s. I had no problem with the first batch (about 3 months ago). I just got in a new shipment, set them up and tried to boot. I get the Systems Deployment Menu and the computers try to connect (dots across the screen), but fail. I've tried both 32-bit and 64-bit KBEs and I have all of the Windows 7 drivers from the driver feed. I can connect other Dell models that I have in the office, just not these.
Downgrading the BIOS
Community Chosen Answer
Try downgrading the BIOS. That's what fixes the issue for me, and it also worked for a guy over here: http://www.itninja.com/question/pxe-boot-environment-restart
If it's something like A13+ making it A12 would likely help as it did for me and the other user in the thread linked above.