Do you have the exact content of the GPF error window?
Is the problem repeatable? You can turn on the creation of the report file in the program settings, and select the "OK files" to be included in the report file. The report will get rather big, but when it crashes, the "bad" file is likely to be located near the end of the file (or rather, a little "after" the end - but you can probably guess what it could be).
What avast! version do you have? (Home or Pro? what build?)
Anyway, can you describe how exactly the error appeared? First, the "Internet program error" appeared in results and then it crashed, or...?