We have a new Latitude E5550 that I'm trying to boot with a Winpe 32bit disk; it starts loading winpe but then errors with

File: \windows\system32\drivers\megasas.sys

Status: 0xC000035a

Info: Windows failed to load because a critical system driver is missing or corrupt

I've downloaded the winpe driver pack and used Windows AIK tools to install the drivers to the winpe boot disk, and confirmed that the megasas2.sys driver is there.  I've done this procedure twice to make sure it wasn't corrupted.

The BIOS came with SATA Operation set to RAID, I changed it to AHCI, neither one works.

This boot disk has worked with all other models of Dell computers (we have a lot).

Can anyone give me some ideas?

Thanks very much,

MG