Luckily, I found the answer after my initial posting here, posted by an anonymous user on tipstrs.com and this solved the problem perfectly...
1-If necessary and able, quit iCal.
2-Open a finder window. From your home directory, go to Library and then Calendars. You should see a file called Calendar Cache. You can either delete the file (scary) ((it's what I did, though)) or click on it and rename it.
3-Restart iCal. It will tell you that it is rebuilding the cache. Once it completes, everything will work as it did before this "upgrade".
That's verbatim, and the only thing that worked for me was to delete it, but it immediately rebuilt and I'm running a-ok in iCal now. I didn't have much stored, so I don't know if by deleting the cache you will delete old entries or not is the only thing...
