Maybe a bug?!?
The above seems to be systematic: I reproduced it again with another file. But only for djvu, not pdf.
Try the following:
- open a djvu file.
- press the joystick button to open the page selection form.
- do not insert any number: just press "OK".
- exit the file via the back button.
Now, the djvu will not open anymore.
If you rename it or move it in another directory, it will open again.
If you rename again to the original name or move it to the original position, it will not open.
Really looks like a bug...