Are you working on a network drive? Or do you have software that would be indexing or backing up your development directory semi-continuously? I believe I've seen that issue in both of those cases.
Short of putting it on a local drive without backups
, I don't actually have a solution, though.
Edit: Just noticed the title of this thread.
It's definitely the sync program that is causing the problem, and I haven't figured out a solution other than pausing it (at least when I ran into it with Dropbox).