I'm currently flying with FSX and have had a problem on 2 flights recently. I am using the PMDG NGX and while level at cruise my VC will vanish and turn into a black rectangle. The scenery covers the upper half of the screen that I can move around smoothly, while a black rectangle covers the bottom half. I go to the top where my views selector is and select Virtual Cockpit and it comes back very laggy and with a flickering mouse. All of the lights in the cockpit seem to dim as well. I wasn't sure whether this was a PMDG error or FSX error so I decided to post it here. Anybody seen this before or have any ideas why it did this? My flight is currently lagging pretty bad with around 7-8FPS, I was getting around 30 before. Thanks. 

Just had this happen again. Anybody have any ideas? This time it happened while clicking on FS2Crew.