Laptop lags for 2 to 3 seconds in all activities.

Hi guys.I just got a laptop from my dad .He bought it 4 years ago.Now the problem it lags or freezes in all activities like when opening folders,playing videos(lag or shutters) in vlc (wmp too) and in browsers.Here is my laptop's specs:



Toshiba Satellite L500-1GJ


Processor:
Intel® Core™2 Duo processor T6600
clock speed : 2.20 GHz
Front Side Bus : 800 MHz

System memory:
standard : 3,072 (2,048 + 1,024) MB
technology : DDR2 RAM (800 MHz)

Graphics adapte:
Mobile Intel® GMA 4500MHD

Windows 7 Home premium 32bit

I tried reinstalling WINDOWS and tried ubuntu nothing solved,the freeze is still the same.Something I saw suspicious about the physical memory usage its uses not more than 900MB.It shows this,

Total 2936
cached 660
Available 2144
Free 1625

when I played a video using VLC.Drivers are up to date.Even tried cleaning the ram and used memtest86(no errors). any suggestions????

Sry guys forget to mention one thing.It lags in bios also when i change to security tab but changing on other tabs not freezing...

Thanks for the reply THRASH ZONE,Here are the sreenshots








Thanks again for the reply....

Just installed utorrent.Not downloading or uploading anything,it's started on startup.Also when I took the ram chip after using a while,I can feel a lot of heat....

Thanks for the quick response.I did a clean boot,the problem still there.In additional,It lags also in the safe mode.

Here are the screenshots,