It's difficult to know
So when you try to install Windows Vista in the virtual machine you get that error. It's very difficult to know what happend, usually that kind of messages are useless.
You can use your Windows Vista disc always and install it again, and again, and again without problems, the activation of the product is another ball game...
I think that you could check the disc and see if it's in good conditions, that's the key, If not, look for another one.