acer 5612 wsmi boot up problems

hi i have an acer laptop which i had for the past 3 months and worked fine all the time up until recently it does not want to boot it freezes after 3 seconds of booting and nothing on the laptop would respond once it freezes so which means i cant even switch the laptop off i have to take the battery out to get it off ,however if i leave the laptop overnight and switch it on in the morning it works it boots into windows i can even watch a movie but not long after that it freezes again any suggestions