If your system was out of memory then it's possible that the file could not be saved. If you are using ArtRage 3 then this is more likely to happen as it doesn't have the additional file save protection systems we added to 4 and 5.

If you could send an email to [email protected] and let us know how large the canvas you are working on is and just confirm which version of ArtRage you are using we can go through some steps to see if we can find out what is happening.