ICal malfunctioning and refusing to be re-installed

Question

I just got my new 24-inch iMac after disposing of my old 15-inch iMac earlier this summer.
I backed up a lot of stuff from my old computer, including my iCal calendars, and thought it would be smart to transfer these to my new setup... not so, it seems. I will try to explain all my actions leading up to the problem:
What I did was just copying all the folders from the Sources folder in the iCal folder in Application Support in my User Library from my old computer and to the same folder on my new computer.
The result was that when I next opened iCal none of the calendars showed up in the calendar list on the left of the application window, and nothing happened when I tried to add a new calendar from the File menu. No event showed in the main calendar view either.
This made me remove all the old calendar folders again from the "user/library/application_support/iCal/sources" folder, but the same problem persisted.
Then I tried to remove the "user/library/application_support/iCal" folder altogether, and this at first seemed to help, because when I next opened iCal it automatically created a new folder with the relevant files and the default calendars (home & work) again showed up in the calendar list. However the next time I opened iCal again the same problem was back, no calendars in the list.
This when I did the second thing I probably shouldn't have done. I decided to delete the entire iCal application so that I could install it again and start from scratch. I dragged the application and the "user/library/application_support/iCal" folder to the trash can and pressed "empty trash". What happened then was that I got this message: The operation cannot be completed because the item "iCalAlarmScheduler" is in use. I had the option to stop or continue, and chose continue. This seemed to delete everything but a small part of the iCal appl. The file in my trash can still shows as an appl file, but takes no more than 56 KB on disk.
It annoyed me that I couldn't get rid of this file (I still haven't been able to), but I thought I might try to install iCal again all the same. First I tried to do it from the OS X disks that were supplied with the computer, but I couldn't find the iCal appl as a separate object that could be installed separately. I then downloaded iCal from the Apple site. The message I get however, when I try to run this installer is: iCal software cannot be installed on this computer. Then the installer just closes. This is my current situation.
I really miss iCal as a way to organize my activities and would appreciate if anyone could help me sort out this problem.

Answer 1

Welcome to Apple Discussions.
You can certainly transfer older data files from one computer to another under most circumstances, but you should always do so using the Migration Assistant on your new machine to transfer your entire user account, and never try to selectively copy bits and pieces of one environment to the other. Doing so under limited circumstances may result in the desired outcome, but the process is severely complicated when OS X generations differ from one to the other - when, for example, you want to move OS X 10.3.9 data to a new, intel-based 10.4.8 machine.
There are several reason why such moves are prone to fail, including the different file structures used across OS X applications between generations, the differing storage locations for such files, subtle and often unapparent but critical differences in PowerPC and intel versions of the OS, and their supporting applications like iCal and the Address Book.
Here is more information on the Migration Assistant:
http://docs.info.apple.com/article.html?artnum=25773
That article outlines the best practices for moving data from one machine to another, and from Mac OS X 10.3.4 or later to Mac OS X 10.4 of any generation.
The version of iCal you downloaded is incompatible both with Mac OS X 10.4 and later, and with the intel platform you attempted to install it on. The way to reinstall, upgrade or update iCal 2 and later under Mac OS X 10.4 or later, is explained here:
http://docs.info.apple.com/article.html?artnum=301408