System Manufacturer/Model Number Dell XPS 15 L502x OS Windows 7 Home Premium 64bit (O.E.M) CPU Intel Core i7 2630QM @2.00GHz Memory 6GB DDR3 Graphics Card Intel Intergrated Graphics 3000, nVidia GT525M (1GB) Screen Resolution 1366x768
Keyboard Backlit Dell XPS 15 L502x Keyboard Mouse Microsoft Wireless Mobile Mouse 4000 Hard Drives 750GB Seagate 7200rpm Internet Speed 2.5 Mb/s down, 0.36 up
Fixed!
I discovered that one of my RAM place on motherboard is ruined and cause problems so i removed my 512m RAM from there and used the 2GB RAM at other connection and its fixed the problem.
System Manufacturer/Model Number Dell XPS 15 L502x OS Windows 7 Home Premium 64bit (O.E.M) CPU Intel Core i7 2630QM @2.00GHz Memory 6GB DDR3 Graphics Card Intel Intergrated Graphics 3000, nVidia GT525M (1GB) Screen Resolution 1366x768
Keyboard Backlit Dell XPS 15 L502x Keyboard Mouse Microsoft Wireless Mobile Mouse 4000 Hard Drives 750GB Seagate 7200rpm Internet Speed 2.5 Mb/s down, 0.36 up