Isolated Storage Available Space

So, I read Microsoft's article on How to: Anticipate Out of Space Conditions with Isolated Storage, but I am confused about something.

I ran the sample code they provided and created 3 dummy files (0 KB) and the reported "spaceLeft" was 9,223,372,036,854,772,735 bytes.

This seems like an invalid size to me. When I use one of the online bytes to MG/GB converters it reports back that I have more space available than the size of my hard drive.

I tried the exact sample they provided as well as the GetUserStoreForAssembly and they both report back that large number.

I know I must be missing something simple, but I don't know what.

Any thoughts?

Thanks,
CT