Hi Keith, I am far away from home (and my folding macs), so it's even more quite here than usual...
Restarting FAH Control indeed would not make a difference, since the actual folding is done by a different program in the background. What might help is if you were to pause and restart folding from FAH Control. This instructs the background program to stop and restart.
Other than that bit, on occasion, there just are no work units for macs to work on (although I don't know how common that is these days, given how long it's been since I saw a Mac). It is rather strange that you would be unable to send completed work back to Stanford. That could indicate problems with the particular server your machine was talking to (the collection server). There's a link to a page with server status information on [url=https://folding.stanford.edu/home/teams-stats/]this page[/url] from the project site, but it does not seem to be working at the moment. Whenever you have trouble with getting work units or submitting the results, you can check that page to see what's going on with the servers.
The biggest difference between time and space is that you can't reuse time.