Laptop keeps freezing, now that I have it running, can't backup.

I've been having issues today with my Dell Inspiron 15.  It keeps freezing and now that I have finally got it running, I want to backup my files onto DVD's but the back-up assistant keeps freezing and not responding.   What can I do?  I have a thousand pictures and videos that I need to backup and it's not working!  Please help!