iCal event alerts won't stop repeating

After the update to Lion 10.7.3, I get hourly repeating alerts from iCal. I've dismissed them but they keep on coming. And the list of the alerts keeps expanding each day. iCal is also repeating past alerts in the list. In addition, the alerts pop up with the Submarine sound, which I also cannot turn off. Needless to say, these hourly interruptions are very annoying. I've applied the Combo Update to try to fix the problem and looked for a solution in iCal and in the system but there isn't anything showing that tells me how to stop the issue.

Imagine trying to record audio and have one of these alerts pop up, as I have experienced. Not only does it cause a glitch in the recording, it also adds the sound to it. I turned off Alerts in the Sound preferences and that didn't help.

There seems to be no discussions with this problem recently.