Back to square one, I see.
I do NOT have any mods or Custom Content!
I do NOT have Late Night.
I have Sims 3, World Adventures. High End Loft Stuff, and Ambitions. However, Ambitions is not installed any more, for that is when I noticed my game starting to mess up. My sims either disappeared or froze in place after a certain time (I don't remember how many sim weeks it was now.). The sim time kept ticking.
My computer is more than capable of running this game, in fact it could run games with much greater graphics and activity.
Processor: AMD Athlon(tm) 7850 Dual-Core Processor 2.80ghz
Ram: 6.00 GB
Graphics Card: ATI Radeon HD 4800 Series
OS: Windows 7, 64 bit
