Wrong Font Display

So I was working with some presentations and everything was fine. But when I reopened the files, something awry happened.

I'm using Windows XP, which means the PowerPoint default font is Arial, whereas the same file from Vista uses Calibri. On normal occasion, Arial and Calibri appears the same.

Back to the problem. The files were originally using Calibri. When I reopened it, the Calibri transformed to a font type which I don't have in the font database.

I thought it was a glitch and thus rebooted the PC but nothing changed. I searched the Net to no avail about this. I tried scanning but nothing comes out. What is actually wrong?

Thanks in advance.

Jam it back in, in the dark.

Dunno what might have caused it, but maybe try importing it as an older Powerpoint File? Like, say it's a Office 97 or something like that.

There's nowhere I can't reach.