Just our of curiosity, have you looked at your oc_file_locks in your DB? is it high?
I was getting an error like this. It ended up being an app. Perhaps a News app or do you have any external facing apps? If you have high file locks in your DB, then look for File locked fixes.
Something like this: File is locked - how to unlock
Keep in mind that I am not sure if your issue and mine are/were the same. I was also getting some News app errors, but there was an update today, that hopefully will fix those.