I was playing a huge game and started fiddling with my slider bars for Military, Social and Research. Frequently they started acting very strange and the totals for the three would exceed 100%. I ignored it, and then one turn, when I really wanted to put everything on research I fiddled with the Military bar for about two minutes, but as I lowered the bar, the displayed percentage actually went up. After that the screen locked up and I mean REALLY locked up - I had to restart the computer.

Hope this helps

Dano