Can't repair vista HELP

Hello,

i have vista home premium 32bit and i notice it became slow and when i use for about 15 minute and double click in computer or any folder the window is complete white.
before i use the dvd and startup repair it works
but it become realy frequency and i tried the same thinhg yesterday in startup repair there is a message says
startup repair could not detect a problem
if you dave recently attached a device to this comuter remove it and restart..

but i have nothing attached and i repeat that like 5 times nothing

so i tried safe mode it blocks when there is the list system...

and now i can't start my computer any more ( it blocks after when there is microsoft and then comlete black)

if there is other way to fix that without format my pc please tell me

i have importent files on it in (c:/) drive and i don't want to lost them
please i realy need help