I have experienced this occasionally also. Pressing the "Start Flight" button causes a cigarbox lockup. I have to kill it in Task Manager, then restart cigarbox. I got the impression that I had not clicked the button good enough the first time. So I try to give that button a firm (yet single) click.
I also sometimes, although not recently, have gotten that "404 remote server not found" error after filing a flight. I ignore it though, because the pirep files anyway.
Now I have been getting (sometimes) "Operation timed out, and Try again." messages after filing. But those go through and get filed also without resending. I just have to refresh the cigarbox. It is strange, that my internet connection seems to close every time I file a PIREP. I wait for it to reestablish, then refresh the cigarbox. I go to the logbook page and my latest flight is there, waiting for approval.