The Compact Framework continues to confound!
I've been doing quite a bit of work with Pocket PC and Windows CE devices lately and, let me say that I've not had to learn so many new tips-n-tricks for quite a while. Yesterday's learning was that, when installing .cab files on a CE device, be sure to extract them from the \Program Files folder.
I'd been deploying our app. onto the device into the Desktop area of the device and extracting the various .cabs - CF, Strings, and our app - from there. The application would install but complain that it couldn't find the framework - even though I had installed it. Then, when I'd start the app. it would throw a Fatal Exception and crash. The solution was to deploy to the Program Files folder and extract from there.