Hi Paddy,
It's not stuck on front row photo page by any chance? For example, if you look at front row on your mac mini can you see the stylised logo under photos?
You know how sometimes it picks up all your photos (and any pictures on your computer), and its holding there?
In finder, also do a search for all pictures and see if you can see the logo there. If you can see it you know it's defiinitely on your mac mini.
Let me know how you go
Michael.