Not sure if this is a problem or just that I'm doing something wrong.
After running CCleaner, Outlook has "lost" my Office 365 credentials and I have to re-enter my password. This is specific to Office 365 has I have some other POP3 and IMAP email addresses ant they continue to work fine.
I've tried turning off cleaning of "Office 2010" but that doesn't appear to have made any difference
I had Office 365 for about six months then moved to Office 2013 (which is all 365 is, same as 2013 but with the monthly subscription) and have not had any issues like you describe.
which should only effect Most Recent Used lists anyway.
also, untick the Office 2013 box, if it's there (that's one of the reasons I moved from the click-to-run 365 to the actually fully installed 2013).
I was finding Office 365 wasn't 'quite right' with the way it installs versus the traditional Office suites.
so are you finding Outlook works fine, until you run CC then the next run of Outlook asks for the mailbox password again or the Office 365 activation credentials?