Windows Vista? Don't try to talk alien...

Let me explain what happened. Last night I got an important e-mail from a friend. I need to download the attachment which size ~432KB off my Yahoo mail. Since it night time I got to get on the internet through my slow mobile phone dial up connection. Lucky enough I got file download and when the download size reach 432KB I got a welcome message from vista:

There is not enough space on VISTA. You need additional 6.98 EB to copy these files.

Funny enough see my free space on the drive? I really don't understand what Vista trying to tell me. Is it kind of new alien message from outer space?