Computer wont wake from sleep

[tshizzled]

Hello,i have a little, annoying problem. my computer sometimes wont resume from sleep when i hit a button on the keyboard, if i do it fires up then just dies out completely. its like someone hit the power switch on the p.supply. it just does this randomely, not all the time but its extremely annoying because i have to boot from scratch everytime. does anyone have a clue wahts wrong.? my specs are gigabyte ma790xt-ud4p,
Amd x4 955 phenom 2
G-skill ripjaws 4gb ddr3(2x2gb)
Seasonic 700w P.S
CM v8 cooler and so on.im running windows 7 Ultimate 64

 

[halchanch]

Last week I bought a Hp Probook 4535s with windows 7 and it displayed similar behaviour, it would not wake from sleep forcing me to hold the power button down until it turned off. I fixed the problem by updating the BIOS. I eventually found my way to a HP site which let me download and update from there!