Macbook Air to Pavilion 27xi Screen Distorted

Hello,

Everyone in our office uses Macbook Airs, which we connect to HP Pavilion 27xi monitors via Henge Docks (using the USB3 and Thunderbolt ports). Recently three people got new Macbooks, and two out of the three of them have extremely distorted screens when they attach to the monitor – the screen is stretched horizontally and is very hard to read. The ones that are distorted ("newer" Airs) have all the same display settings as the ones that look right ("older" Airs). We've also connected the computers to different docs and monitors, and these two "newer" computers always do this and the "older" ones always look fine. We're at a loss as to what is causing it. Any help is appreciated!

Here are the specs of both types of computers:

"Older" Airs:

OS X Yosemite, version 10.10.2, MacBook Air 13-inch, Early 2014

Processor 1.4 GHz Intel Core i5

Memory 4 GB 1600 MHz DDR3

Graphics Intel HD Graphics 5000 1536 MB

"Newer" Airs:

OS X Yosemite, version 10.10.2, MacBook Air 13-inch, Early 2015

Processor 1.4 GHz Intel Core i5

Memory 4 GB 1600 MHz DDR3

Graphics Intel HD Graphics 6000 1536 MB