screen freezes, when full screen

my screen freezes whenever i play newer games or go fullscreen while watching youtube videos. it like makes a weird sound then freezes and i have to force power it off. maybe my graphics card isn't getting enough power?
please help!

here are my specs:
AMD64 X2 6000+ 3.0Ghz Dual Core Processor
Socket AM2+ / HyperTransport 2.0
2GB High-Speed DDR2-800 Memory
VGA-Out & DVI-Out
RAID 0/1/0+1 Capable
22-in-1 Media Reader
Onboard 10/100/1000 Gigabit LAN
Onboard High Definition 8-Channel Audio
(2) USB 2.0 Ports
Visionman Gaming Chassis
585 Watt Power Supply
nvidia geforce 8400 gs

 

o i forgot here are my temps

 

bump.

 

can anyone please help me!

 

ok i updated drivers and everything seemed fine but today i just install 2gb of ram and it seems to crash just when i am web browsing for no reason. can any one please help me!!
as u can see i havent got many responses:cry

 

did the crashing/freezing occur just after installing the ram? your motherboard might have not configured it correctly. check with the manufacturer on the proper bios settings.

run memtest to make sure your ram is ok.
http://majorgeeks.com/MemTest_d350.html

you might also want to run a hard disk SMART scan. I think you have a seagate drive
http://majorgeeks.com/Seagate_SeaTools_for_Windows_d2858.html

 

well it started before i installed ram then i updated driver for my video card and it worked pretty good then yesterday i installed some ram and it started crashing for no reason i would just be web browsing or something

 

i would go with a base amount of ram to start (if you have multiple sticks, try 1 at a time) . keep doing it, until it runs stable with 1 stick in at a time. And if you have problems with one, then you know what the culprit is...

 

sorry for not getting back been busy. thanks for all the replies i will try all the above posts