I've got an M6600 that is configured with an SSD and two additional hard drives in a RAID setup. Whenever I try to image the machine with SCCM, it applies the OS properly to the SSD (Using Disk 1, partiion 1 as the target) and reboots to apply drivers etc. When it reboots to do the "Install Configuration Manager" step it looses its way and dumps out to an unfinished image (WIn 7 x64 without additional apps, device software etc). Looking at the computer, the RAID array does not have a drive letter on it. I can add one and the drive will then show up on the system. The contents of the drive is the Task Sequence cache folder that was getting it imaged.

I have the same configuration with an M6500 and it images WITHOUT issue.

I am using the latest Intel Drivers posted on Dell website and have added them to my PE disk as well. Not sure what else to try.