mouse and computer freezing up

my mouse and computer keeps freezing up using windows 95 it dosn’t matter what i’m doing in a program or on the net or just moving the mouse to get rid of screen saver it just lockes up and esc or atrl alt del dosn’t work my other computer does thesame thing so on one i refomated and installed windows98 and it still does it so i have windows on one that locks upmouse and computer and windows 98 on the other and both are locking up do you know what the problem is and how to fix it help!!!!! please