Sorry to hear you're having a problem there. I've done some testing here and managed to reproduce the problem now.
When you import an image to layer, the positioning toolbar is shown to allow you to resize and move the image around. If you specifically use alt+left click at that point when the pan tool ( 4 way arrow ) is active to attempt to resize the image, a crash occurs.
To avoid the problem occuring, use the scale tool in the toolbar ( the magnifying glass ) instead of the keyboard alt+left click shortcut as this doesn't crash. The alt+left click shortcut wasn't intended to be active at this point, an oversight on our part! I've just added this to our buglist here for us to look at. I hope that helps, thanks for letting us know!
In the event of a crash, ArtRage attempts to save a temporary file to your user data folder in Windows XP e.g:
C:\Documents and Settings\<your user name>\Application Data\Ambient Design\ArtRage 2\ar2restart.ptg
So, if you've had a crash it may be worthwhile checking there to see if ArtRage was able to successfully save the painting.