notbob,
I have just tried this and what you say is correct. This seems to be since the latest release 4.1.1.1 as I tried it prior to upgrading and the Sidebar *and* the Toolbar remained hidden after restarting MEP. With the latest relaese they both reset to being visible after restarting MEP.
They do remain hidden for the duation of a session though, so more an annoyance than anything else.
If you like, I will submit this as a bug.
Alan Monaghan
Kirkcaldy, Scotland