Here is a link (thank you, Stephanie) from Google Calendar that might help with your issue:

Link http://www.google.com/support/calendar/bin/answer.py?answer=59820&topic=8580

We're currently investigating reports from users who are unable to view some of their events after logging in to Google Calendar. If you're also experiencing this issue, please be assured that the events are still in your Google Calendar service (unless you've knowingly deleted the events from your calendar).

While we investigate the cause of this issue, we recommend disabling Google Calendar's Weather feature to see if you're able to view your events. Please follow these steps to disable the Weather feature:

1. Click "Settings" at the top of any Google Calendar page.
2. Select the "General" tab if it isn't selected already.
3. Under "Show weather based on my location," please select "Do not show weather."
4. Click "Save."
5. Sign out of Google Calendar.
6. Log in to Google Calendar again.

If you don't have the Weather feature enabled in your calendar and your default view is set to the "Day" view, please change your default calendar view to something other than the "Day" view to see if it resolves the problem. To do so, simply follow these instructions:

1. Go to "Settings."
2. Select the "General" tab.
3. In the "Default view" section, select the desired view from the drop-down menu.
4. Click "Save."
5. Sign out of Google Calendar.
6. Log in to Google Calendar again.