Dave,
If Lightroom believes you are importing from a temporary media device like a CF card or SD card, the application will only allow you to copy those files off of the device. Importing in place or "adding" directly from the card will be disabled. Your OS update probably correctly identified the nature of the device and Lightroom then respected the behavior we've had in place since Lightroom 1. I'm sorry this is interrupting your existing workflow but we have serious concerns about customers accidentally importing referenced files from a card that is subsequently reformatted in the camera. We've seen confusion around preview availability within Lightroom being mistaken for Lightroom actually "owning" the original assets.
Regards,
Tom Hogarty
Adobe Systems