Arbitrary file access privilege changes

My rig is an i7-930, 12GB, Nvidia 250GTS, Win7 64 bit Home Premium with all updates current.

I do a lot of photo editing with Nikon software and CS5. My critical problem affects CS5 64bit, Nikon CaptureNX2 - 32 bit, and Nikon ViewNX2 - 32 bit. Suddenly last night I could not save labels in ViewNX2 or files in CaptureNX2 and CS5. The error message was the red circle with an 'x' saying I did not have access privileges to change the file, that I will have to go to the file and change the access privileges in the files/info properties in the operating system. I can save files with a new name, I just can’t edit and save again. I have over 40,000 image files; changing access privileges would be close to impossible, even if I knew how to do it.

I took a look at the properties of the folder where the images were and, for some unknown reason, the whole folder was marked as 'Read Only'. Unchecking that attribute did not solve the problem, I still can't edit the files.

This problem does not occur in other programs, notably Word and Excel 2003.

This is just baffling and has stopped my photo editing in its tracks.

Any suggestions? Thanks

Update. As trial measure I took ownership of one of the image folders, even though I am in an Admin user account. Now I am able to edit in that folder. I did NOT take ownership of another image folder, although I am now able to edit images in that folder without error messages.

OTOH, when I tried to edit an Excel file just now I got an error message that said it was Read Only. I looked at the properties and it was NOT read only. Then, went I went back to save the file Excel still said it was read only and prompted me for a new name. I opened the save-as dialogue box and simply saved with its original name, and it saved the file.

What gives with this inconsistent, random, and arbitrary access privilege changes?

I really need some help here or I won't be able to use this computer in a work environment. Thanks.