Isn't 2.2.1 the current version? Not that that would mean that 2.2.1 shouldn't be able to open the files. It may be redundant, but are you sure that Capture NX2 has access and permissions to access the folder with the raw files?
Depending on which camera you are using, it may just be that your version of Capture NX2 is too old to support its NEF files. In that case, you'd need to update to the latest version, which I believe is 2.4.1.
Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit. - Nicomachean Ethics
Sun 05-May-13 08:21 PM | edited Sun 05-May-13 08:22 PM by jrp
The problem usually presents itself when using a not updated version of the Nikon software or when running out of memory. A good solution is to make sure you keep up to date all software and using an external drive for the cache of both ViewNX, CN2 and for Photoshop if that is also in your workflow.