here's what's happening:
We shot pictures with a BRAND NEW canon 40d, using 'san disk' memory cards (Extreme IV 4gb and also Ultra II 4gb ) and then used a san disk reader to load images into our mac computer; i can see & enlarge thumbnail images, but I cannot open images in photoshop or lightroom.
Then, I use the same memory cards with both of our old canon xti's/rebels (using same reader as well) and the images are fine and able to be opened in PS or LR no problem.
So I buy another NEW camera, this time a canon 50d, and the same freakin' thing happens but even worse-- we cannot open images in PS or LR nor can we even see thumbnails!
Help!

It sounds like you need a plug in for photoshop. What version of PS and LR are you using?

Hi Kari,
I'm using PS 3 and LR 1.1.

When new cameras are released after the release of the software, you need to update your software. If you don't, it won't recognize the new camera. Try this...
http://www.adobe.com/support/downloads/detail.jsp?ftpID=4039

Edit: Oops, I just changed the link. Wrong one at first.

Make sure and run your mac's software update to check for RAW compatibility updates - a new one just came out for the 50D.

As for PS/LR, make sure you have all updates installed for those as well. This is a very common problem for people who don't bother to run updates - believe me, they're there for a reason!

If you were in our office right now, my wife and I would hug you until you passed out from our gratitude. It worked! We can smile again! A thousand blessings on your head and on Trevor Meeks too. Watch out, Meeks, we WILL get you.