So my game runs perfectly fine, except for one thing.
A few weeks ago I started playing uip as normal after awhile of not playing, when all of a sudden my n-hood starts lagging. At first I ignored it, then the graphics started flashing. I ingored this too, because again my game runs flawless in every other aspect. Now it's gotten to the point of where it gets to the n-hood view and hardly even nudges every minute or so and i can hardly move my mouse because its so laggy.
Thinking back, I believe the lagging started after I installed Teen Stuff but I uninstalled that and the flashing graphics stopped but the lagging is still there.
This is driving me insane, so what do I do?
I have a fairly new graphics card that usually, as I said, runs the sims flawlessly so thats not the problem.
I've tried stopping background processes and such. And the useshaders cheat seems to help slightly, but it takes FOREVER to even get the cheat screen up, and woe betide me if I mess up inputting it.
I run a Windows XP 2002 Version with 2.49 ghz and 376 MB of RAM. I also have nVidia gforce x5500.
But like I said its run fine in the past with these exact system specs. And it also runs perfectly fine in the actual game mode, CAS, when I'm playing with lots. It runs flawlessly, which is possibly the most frustrating aspect of this problem because I can hardly ever play my lots anymore.
What Do i do?? =[

Your graphics card is actually very old, and underpowered - it's not a good option if you're running Seasons, however given that you're not running any other EPs you should be able to manage with it. Have you turned down all your graphics settings? Checked that you're not overheating?
Also, is this only in one neighbourhood, or in all? If it's in all, what happened when you tested with clean user files?

376mbs of ram is way too low for xp you need at least 512mbs i have 2gbs

Eep, thanks for pointing that out, carly - my eyes just floated over it. On another note, how did you end up with such an odd number? RAM is almost always in multiples of 256 Meg.