> 	NewWindow.document.write ('<img src=');
> HTTrack now tries to 'solve' the problem with the missing 
> filename after src=. So, HTTrack generates a file with to 
> following content:
> 	NewWindow.document.write ('<img src=');.html

Try to disable the "attempt to detect all links" option. I 
will fix the problem forr the next release anyway.