Can you see what the error the blue screen is showing?, also is it ocuring at random intervals or when specific software is ran?
A common issue when it comes to seeing new errors/BSODs (your blue screen) is memory, run memtest (http://www.memtest.org/#downiso) and see if memory has been corrupted. You need to boot it using an external medium so download the ISO (disc image) onto a new clean CD/DVD, or if you have a flash drive you can boot into it that way as well. There are many guides posted online if you do not understand how to do it.