My desktop keeps freezing running vista home

Hello,
my computer has been freezing all the time. now it wouldn't start up got a black screen tried again and it did some trying to repair your computer scanning for problems. than asked me to do a restore i said yes it started up let me and and as soon as i went into a sight it froze again and still freezing before total startup the screen just goes wacky and it freezes. get these red lines and distored picture and it freezes