Over the past couple of months I have assisted several customers with driver and imaging issues on newer Dell laptops (E7240 & E7440) and all were specifically related to not having applied Microsoft KB2685811 (KMDF1.11). This is a known issue and has been blogged about before by Dell but the word does not seem to have spread enough so I thought I would mention it again in an effort to save you some time and effort.
Make sure you pay attention to the notes anytime you download new driver cabs and you will avoid the extra aggravation of your OS deployments failing.
Grab the download for KMDF
Follow an example of how to implement it here
I have tested option #2 and it does work but he assumes you know to change the package ID.
Additionally my colleague determined that you will need to modify this slightly if your environment is still 2007 and you are running your task sequence from the distribution point rather than downloading locally. You will find his comments on the original blog but I have provided a screenshot below.