I was just working with the live 'painting' plugin and my Vista P.C. froze.
I got an error message:
[atan2 DOMAIN error]

At the bottom of the screen instead of saying 'Xara Xtreme 4 Trial' it gave me:
'177 Xara Xtreme 4 Trial'

After investigation (I think I first went onto XX3 and then returned), I saw a stack (probably 177) of:
'Xtreme.exe'
I scrolled down and after a while I found my 'Untitled' (I know i shold have saved it before) file at the very bottom of the stack. I opened it again but it was still frozen.

I opened the 'Task manager' and saw the stack of [xtreme.exe]
After attempting to close a couple of them, the whole lot vanished and I lost my file.