If you want to just view and edit, you can just right click on the image and then Open it in Editor.
And regarding the file size error, your image pixels must be greater than supported by Organizer.
I think the maximum pixel size for photos in the Organizer on computers with more than 1 GB of memory is 54 megapixels, or about 7524 x 7524 pixels. So if your image is greater than that, it won't show.
I have some very large .psd files in my collection (over 100 MB in size) and those won't show as thumbnails. I get the file too large message. What I do is create a smaller sized .jpg file from the .psd file, put the .psd file in a stack with the .jpg file, and select the .jpg file to be at the top of the stack. That way I see a preview of it in the Organizer collection.
Thanks..I'll give that a try.
There exists a limit to display the thumbnails of images in Organizer. Till PSE10, the limit was 54 megapixels. In PSE11, the limit has been increased to 72 megapixels.
You may read the article which can help you increase the maximum limit.
Let me know if that helps!