Doesn't happen here, so it's probably related to your system configuration.
Is this the first time in the past few weeks you've tried to save a map?
Are you running as Admin or a Least-Permission account?
The first file isn't exactly tiny, but the second one is, so it's probably not due to fragmentation - but just in case, are you running on a SSD that's seen some heavy use or is nearly full?
We can trivially disable this warning, but I'd like to understand why it's failing. Unfortunately Windows isn't setting the last error code, which is weird.
