I recently purchased a new e7440 for an employee and swapped out her old e6410. She has an e-port+ advanced dock and 2 22″ monitors. The setup worked great for years.
Shortly after she started using the e7440 the secondary monitor seem to go to sleep. Power cycling it fixed it. I swapped the monitors around to see if it was the DVI port on the dock or the monitor. Same behavior.
I swapped out the dock for a standard e-port+, same behavior.
I finally got around to googling to see if it was just this e7440. Unfortunately, or fortunately, it’s not.
I found this post E7440 Display Problems (http://en.community.dell.com/support-forums/laptop/f/3518/t/19532685.aspx)
While the issue in the post was flickering, this fix resolved my issue as well