I recently completed 8 hours of single country play (as Germany). This was the first time I had tried this mode-I like it.
I had some concerne that somethig might be amiss as after each Diplomatic phase and the start of the military phase, the screen would go dark for a second or two. Also, Germany's research was painfully slow-one item taking 9 turns.
By July of '15the cusor was getting "sticky" and the black screen before the military phase lasted 10 seconds. This was getting bad so I had to try turning more stuff off (which is not necessary in the 2 player mode-I even run Norton scanning during the game w/o trouble). Anyway, I already had any excess stuff off except for the task manager running on the second monitor. I turned that off and the second monitor-and viola!-it was working smoothly again. Not only did the remaining turns I played last night, from Aug '15 to Jan/Feb '16 play smoothly, but the tech research suddenly-and I mean suddenly, started to work. There was no more screen blackout at all.
Why the second monitor should have an affect on the game playing (or maybe it was the task manager-or both) is beyound my understanding. There was absolutely not other change when I paused at the start of the Aug '15 turn. The PC nor the game was restarted, but it suddenly began running as well as the 2 player mode from what it was doing-no small difference there.
I was more into playing the game last night rather than testing, so I did not check to see if it was the second monitor or the task manager that was causing this-I will test it later today.
Personally, I never would have suspected a second monitor or task manager have such an affect on a game-hopefully this will save someone else some trouble.
BTW I'm using Vista now