Hi,
1. What is the complete error message are you getting?
2. When exactly do you get this blue screen error?
3. Are you able to boot in desktop after getting this blue screen error?
4. Did you make any changes to the computer before the issue occurred?
I would suggest you to try the steps from the link below which would help you to resolving, stop (blue screen) errors in Windows 7.
http://windows.microsoft.com/en-us/windows7/Resolving-stop-blue-screen-errors-in-Windows-7
(Holds food for Windows Vista)
Hope this information is helpful.