Hi,
Could you find the physical file in the store?
1. Search for the file name in node_properties.string_value column.
2. Search for all properties for the GUID and look for the content property.
3. Take the content URL and see if you can find the physical file in the content store.
If the file is there and valid (you may have to fix the extension), then let us know and we can try something else.
Regards