weard problem

Acer Aspire 8930 Specs:
Size: 17.4 x 11.8 x 1.5 inches
Weight: 8.8 pounds
Processor: Intel Core 2 Duo T9400 clocked at 2.5 GHz
RAM: 4 GB DDR 2 RAM
Hard Drive: 320 GB SATA HDD, 7,200 RPM
Optical Drive: 8X DVD ± RW
Display: 18.4 inch TFT display, 1920 x 1080 pixels
Graphics Card: Nvidia GeForce 9700M GT 512 MB VRAM
Wireless: Wi-Fi – 802.11 a/g/draft-n, Bluetooth 2.0 + EDR
Operating System: MS Windows Vista Ultimate
Ports: 4 USB 2.0, DisplayPort, Ethernet, HDMI, Headphone and Microphone jack, Modem jack, VGA out, eSATA, 6 in 1 card reader, ExpressCard slot

Still, I say.

Do you have egnuf memory?

maybe you have like:
Cuse they take alot memory from your game.
So Open yout task manager and see. When your in-game or out-game.

EDIT:
To see your memory usage.
Do this:
1; Open Task Manager
2; Go to Pefformens ( Sorry miss spelling.. )
3; At the bottom to the windo ( Windows task manager. OFC )
4; Pyisical Memory.
5; Free...
How much free you have?
if 1-100 thats bad.
And over is okey and good...

Well, both your RAM and your processor is better than mine (3gb and 2.44ghz), and I've never had problems with that.

total 3068
in cache 144
free 11
when im in game

out of game
total 3068
in cache 1919
free 619

Well, thats bad.
try gamebooster or advance system care..

Clean your pc a little too

/me