Last question first: AC is written in Visual Basic 5/6? There's been "requests" to re-write it in .Net but that's been shot down. Understood the reasons but I'm not the PM of the project so I have no say.
I highly suspect the panel that the images/files displayed is a webpage panel. Any application that supports a file to be opened in a web browser (such as Reader, MS Word) should not have any significant issues... pretty good way to support file formats actually so the Dev doesn't have to write a whole bunch of extra code to support new formats.
You can always right click on the file and "open with default applicaton" as the other alternative. Annoying but works.
