Double-clicking on a Fireworks native PNG file in the Windows 98 Explorer causes Explorer to crash.
Explorer is set to View > As Web Page. There is a 4k buffer that the PNG is read through in Explorer. This buffer limit restricts all records, even unknown ones that don't fit this buffer size. The Fireworks PNG format includes all of the database information used by Fireworks. This data exceeds the buffer limitation in Explorer, causing Explorer to crash.
Microsoft has logged this as a bug in the IE database to be fixed in IE5. Users are recommended to avoid using the View>as Web Page option in Windows 98 until IE5 is released.