J. River Media Center Problems on Vista
it took over without asking as the preferred application for viewing JPEGs, then didn’t work properly (you really really don’t a program that has a countdown-based evaluation mode to be the default JPEG viewer EVER). After I uninstalled it, notepad was the preferred application 
EDIT: maybe I was a little hasty, check the comments.
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January 29th, 2007 at 2:52 am
J. River Media Center does not take over without asking: there’s a dialog box that comes up during install asking which types you want it to take charge of.
We also restore them to previously used values. It’s possible there’s a bug, but probably not.
Did you report the problem to Interact, our support site?
http://yabb.jriver.com/interact/
We handle bug reports and user difficulties there.
Thanks,
John Gateley
Media Center Developer
J. River, Inc.
January 29th, 2007 at 8:39 pm
OK I didn’t notice the dialog box but am normally fairly watchful for this sort of behaviour from quicktime, winamp etc.
However I know I had a nero program displaying images as default before and it certainly wasn’t restored. The problem could be I was running media center on Vista, maybe it is not fully compatible?
I didn’t report the bug as I was only evaluating it quickly as I have noticed iTunes to hang on Vista, I couldn’t see whether ipod based smart playlists were supported so gave up.