Hello. Thank you for continuing to reply. Yes, I am presently using the "latest" drivers supplied by Dell which are Intel drivers. The driver for the AC7260 is version 16.1.3.1 dtd 08/01/13, Proset is 16.1.3.0. These are packaged together on Dell Driver and Downloads for these systems e7240 as the latest Dell tested drivers for Windows 7 Pro 64-bit.
I have also tried the newer 16.6.0 dtd 11/13/2013 found by running the Intel driver update utility with the same results. If proset is uninstalled, all works as expected.
So, either there is an issue with Proset or perhaps more likely, an issue with a setting in Proset as I am certain that I had this working with this latest driver/proset version, but have no idea what has changed and have uninstalled and re-installed all drivers for this system.
Thank you.