Error Writing issue with new update

I got the newest update last week, and so far I have had an issue on 3 different files with this error.

I am working in a file, make some changes and go to save and it saves, later on still in the same file, make some more changes and go to save and I get a Read Error message that says the file is in use.  Then from that point on if I try and save it it says, Error Writing ...filename... Unable to save the file. Try saving the file to another location or with another file name.  

So my only option is to do a save as... which works.  Then I go in, erase the original, and rename the new one back.  What a pain.  

Not sure what I can do about this, other than this.