I think this very same 'Saving error' happened to me also, except that I could not save any document and I could not copy to clipboard from xara. Xara gave some error massage to that as well.
Also Xara emptied (deleted) my named files from the current project folder. Luckily I was able to recover some work from the backup files.

This was my first experience with the latest version of Xara.
I am afraid to use v.7 now so I stay with v.6 for some time.