Not enough info here. Your hard drive crashed and you replaced it. But(the great big BUT) did you install the exact same OS version you had when you installed PT7.1? If you have a newer version of OSX now, you may never get the old version of Pro Tools working again(this would be Apple's fault, not Avid). The good news is; the Mbox Pro2 still works with the latest versions of PT(assuming you install the driver which is a separate download from the Legacy section for hardware drivers). You can access drivers by clicking the link near the top of this(and every) DUC page named
Additional Resources. The band news MIGHT be that its time for you to buy a newer version of PT that will work on your current version of OSX(that same link above can also lead you to a page showing which version of PT works with which OSX version you now have)
