I have recently noticed that when ever i go to load a movie or video, both online and offline my computer completely freezes to the point of no return, i have to manually restart the computer. This has only been happening since i reinstalled xp after uninstalling vista, is this a software problem or driver or windows problem???

System Specs
Pentium 4 3.0 ghz
512 mb DDR ram
Nvidia NX 6600 GT 128mb
onboard sound card
windows media player 11 installed
inter video winDVD 7 installed

after you installed XP did you install the motherboard drivers? are there any devices in device manager with a yellow question mark or yellow triangle next to them?

I would do a low-level format.

SM Bus Controller is a yellow question mark with a small yellow exclamation mark next to that, it says in device manager that the device isnt configured properly

Let windows search for the driver on the motherboard cd.