Could someone tell me what this .temp thing is and why it's messing with me saving?

So, the dialog box in the attached screenshot appears pretty often when I try to save a score, but when I try again it doesn't appear and it saves normally. This has happened in both 3.4.2 and 3.5. It only started happening maybe a few weeks ago. I'd like to know what that dialog box is actually saying and if it's a real problem or not. Also, if at all possible, could we make it stop doing that every other save (literally)?