could not save as..... because the file is already in use or was left open by another application

I've been a CS6 customer for many years, had a recent account problem that was solved by a reinstallation process - helped by Adobe tech support - after which all was fine.

But I've suddenly found that I can't save files that have been opened in Camera Raw, and I gat the following message:

"could not save as.....  because the file is already in use or was left open by another application"

As I work with RAW images this gives a major problem.

I've looked through the forums, this seems to be a regular issue but covering a range of problems.

This is a new problem, no changes of settings or processes that could possibly have triggered this.

Please help, I can't work if I can't save images.............