The stock calendar in Ice Cream Sandwich has a setup screen where you can choose which of your calendars you'd like it to display. I've got two Google accounts and each one has four different calendars. Apparently, this calendar can't keep track of which ones you've checked to show and which ones you've left unchecked. When I tap the "Calendars" button at the top of the screen and select a couple of calendars, it remembers my selection for a while -- like if I exit to my home screen and come back to the calendar. But if I use the phone to run a couple of different apps (doesn't seem to matter which) and return to the stock calendar, it seems to have forgotten my selection.
I've been using a number of other calendars -- Business Calendar, Calendar Pad, and Jorte -- and they all work fine. Hmmm. Anyone else seen this weird behavior?