I am really annoyed with Mountain Lion. There have been a number of problems, but the most recent on is particularly frustrating. When I switch inbox accounts, then switch back by clicking on its name under "Inbox", none of my emails appear. The entire column is blank. When a new email arrives, that email shows up, but not the older ones. The only solution is to quit Mail then relaunch it. Anyone else have this problem and if so did you find a work around? Mac Pro 12-core.