the blue screen showed most of time because of ram error , or remove one ram or add a new ram or upgrade for example from 512 to 1024 after windows setup.
you can setup windows again and it will fix it.
if blue screen showed up again ....
you can go to setup page by hitting Delete or F2 ( depend of main board you are using ) then hit enter after selecting load safe default menu and save and exit.
if the pc wont start again , remove your device,s ( cdrom and other device,s in pci slot,s ) then try to start pc again.
if this happened after installing a program try to boot with safe mode by pressing F8 button after resetting the pc and uninstalling the last program installed in your pc.
i hope it work.