ical doesn't keep changes

Whether I delete an entry or simply change the text in ical on my Mac, it immediately reverts back to what it previously had. I'm running 10.7.5. I have been using a memory stick to export a copy of my calendar, import it to my laptop, make changes on my laptop throughout the week then import back into my desktop later in the week. I have deleted the other calendars using the "calendars" drop down in the upper left corner of ical, but that has not helped. Even though I deleted the old versions, obviously the data is still somewhere and keeps going back to it.

When I look in System Preferences, I do not have calendars selected for iCloud so it shouldn't be getting re-synched from that, right??