no sweat about the english. i'm not a native english speaker myself.
if i get you correctly, there are 2 things you can do:
1. check the file with os tools.
both gdi+ and quartz offer tools for reading image files in various
formats, so you can check before importing.
2. you can use AE to check.
use AEGP_StartQuietErrors, then do a test render and see if you get an
error without the user seeing it.
you can then decide to dispose of the image or notify the user.
don't forget to set AEGP_EndQuietErrors when you're done.