keyboard and mouse lockup

i have a AMDk62/3dnow-300Mhz, new soundcard just put in new memory and video card from another puter that works. new modem, 48x cdrom, and a 1st mainboard mother board. My question is my computer will lockup the keyboard and mouse alot usually when im on the net (AOL service provider)and at first I thought it might be the memory so i took it out of another computer that works and didn’t fix it then i tried a video card from a different computer (S3-savage4/32meg ram)and i still have this problem of the keyboard and mouse stop responding any help would be apprieciated thanks