Chew,
From what we've read on that exception, it usually occurs in two scenarios:
1) If you specify a URI to an image resource in your project somewhere but the URI is wrong (i.e. you moved the image but forgot to change the URI).
2) The pixel format you use for your image is incompatible with WPF.
What we recommend is to first try and figure out which image it is happening on. Comment out the code for the image source on that image and see if everything works again (it should since you don't reference the image). Then double check your URI. If that is correct, try swapping in another image from the same folder. If that causes the exception again, you may need to try opening your image in Photoshop or whichever drawing app you use and resave it. See if that helps.
But I don't believe this is anything we are doing, it is something with the images themselves or a bad URI. All we do with images is forward your image source to an Image control in our templates.