RW2 files failed to display or open this morning

Hi, I have been working with RW2 files on this PC without problems for 6 months and all was normal last night when I shut down as normal. This morning I switched on to continue my work and the window with RW2 files showed just blank icons. I clicked on one and got the message "unable to open this file type, no supporting program" or similar, usually it opens a preview window at the side and will open in Windows photo viewer with a double click, but now nothing. JPG files still display and work fine and all the RW2 files open normally in lightroom 3.6 when I open that. I rebooted but the problem persists. I then looked at system restore and there were no restore points for this month and it gave a list of 5 programs it would erase, which I had updated/installed a few days earlier so I decided to look for another way first (I have very bad internet so do not want to have to download those again). Everything has worked fine with those updates for several days so I suspect it has nothing to do with them. Does anyone know of any possible causes and simple cures for this issue (it might have done some automatic updates in the background yesterday, but I don't know).

According to that site the Camera Raw plug-in is for use with photoshop and elements which I do not use, I only have lightroom 3.6 in which the files still work but they have stopped working since this morning in windows explorer so it would seem to be a codec problem, or does camera raw work as a standalone codec. Either way something must have been installed previously.