We are having problems with Dell 7275 Latitude and McAfee DE on sleeping mode and power-on button. When the Notebook goes to sleep sometimes it shows a message indicating, "not boot disk found", others when you press the power button, it doesn't start inmediatly. If you do the same test without DE, the Notebook changes the behaviors and responds immediately to this actions.
We also know by a local McAfee support that product 7275 is not officially certified to DE.
I hope this could help to understand.