Running  latest updated version:  Outlook Mac 14.3.9 and Mac OS  10.9.2.

Inbox email disappear without explanation.  Some of them may appear in the deleted folder but other do not.

Only use one POP email account (Comcast) and have configured it with no changes for a few years.  

This problem seems to be tied to the latest update of Mac OS but I cannot be sure of that.

Any ideas or help?

Thanks very much.