Dual monitor reverts to main display only after few seconds

I have an HP Z210 workstation with two LG 24EA53 monitors running Window 7 Pro 64bit.

The two monitors always worked fine until a little while ago. Now the computer will detect the second monitor and will connect and display as clone or extended desktop but after 2-3 seconds it reverts to the main display. Even though it says "Do you want to keep changes" and counts down from 15-20 seconds it switches back to single display after only a few seconds. The kicker is that if you unplug the main monitor which is working the second will display correctly and also the dominant display ie. the one which will continue working despite another display being plugged in can be changed by selecting that display as the main display. I have to quickly switch the main display in display settings to do this while both displays are on in order to do this.

So to clarify both displays work and can be detected and even used but only for a few seconds before windows automatically selects "show desktop only on 1" when both are plugged in. Otherwise either display will work fine if the other display is not plugged in no matter what cables display port or DVI I use.

I've tried updating graphics drivers, resetting the monitors, checking refresh rates and resolutions all to no avail. Any help would be much appreciated.