I was guessing that it was a RAM problem. Thanks for your explanations about the 3GB switch. I hadn't heard it explained that easily before.
I had to laugh when I read puttincomputers's advice to get a new computer to replace my antiquated one. He's so right! I've been putting that off for as long as possible. CIV5 was released on my birthday and I knew I shouldn't bother with it because of the system requirements. (But, from what I've heard, it's not all that great anyway -- at least I've been convincing myself of that.)
If I was getting a new computer, do you guys have any suggestions as to the specs it should include? (Other than playing big games like this, my "biggest" application would be video editing projects.)
Again, thanks for your comments. Someday I'll be able to play C2C!