#2 is an on-going problem for me and I do not use a server. The only way I can resolve this is to close out completely and re-open the application. – Not very efficient.
#1 happens to me all of the time. At first the only way to ‘find’ the other Excel files was to start the shutdown procedure and eventually Windows would as if you would like to close it without saving. The Task Manager didn’t show it was running prior to this, so you couldn’t do anything about it from there. Eventually I caught on to another way to have the files “re-appear” – If you block a section of anything and then print it to display, all of the other files show up again. Time consuming yes, but it is the only work around I have discovered.