it does not stop providing service, but there may have been an issue with logins on some versions. do this. Select FILE/HELP => Check for updates.
Let MT update all files, then restart MT, EVEN IF NOTHING was updated.
if you see it fault again - on the main dashboard window, click on SOURCES on top right, then right click on Fidelity row and select Force RELOGIN. Do not touch anything at this point until it is done logging in (might take a minute).
Let me know if it works. And as @wilburpost2 mentioned, it will not work on Win 7, though that is not an issue in your case, but definitely something to keep in mind for others reading this.