Inspiron 1545

Hello,
I have a Dell inspiron 1545 and recently everytime i start it up it does a disc check then when i finally, if i am able to get onto the main screen the whole thing freezes and i cant get anything up. After finally managing to get to scan my computer there are no viruses to be found and i used dell's support computer scanner which solved the disc checking at the start but now i literally get onto my start screen then the whole thing freezes. Any ideas what i can do or what the problem may be? Cheers