Disable two week view in the Mountain Lion Calendar App
Another (and more definite way) to get this fixed:


Close the Calendar app.
Edit ~/Library/Preferences/com.apple.iCal.plist and REMOVE the following keys:


CalUIDebugUseIPadStyleEventLayout
last calendar view description
IncludeDebugMenu
CalUIDebugDefaultDaysInWeekView

Save and restart Calendar.


You may need XCode or the PList Editor to edit the file (or use plutil to convert to text, edit with TextEdit and convert it back to binary).