Ok, I solved my problem thanks to Austin Kinsella1's help in this Post:
http://discussions.apple.com/thread.jspa?threadID=1949244&tstart=0
ray-gunn, you might want to try the method I used:
1) Delete all the iCal files and also the User/Library/Application Support/syncservices/local/ folder. Of course first make a back-up of this folder as you will need to restore it at the end.
2) Next launch iCal and let it run for at least a minute to make it sure it does not load any data. Then, once you are sure there is absolutely data in it, quit it.
3) Now launch iSync and in its preference panel, select the "Reset History" option.
4) Now launch iTunes and in the iPhone window click on the "Info" Tab. There, select the "Sync iCal calendars" option. Make sure you DO NOT select the "Do not sync events older than xxx days". Also make sure you DO NOT select the "Replace information on this iPhone" options at the bottom of the iTunes window.
5) Now sync the iPhone. It should copy all the data on the phone to iCal.
6) Lastly restore the User/Library/Application Support/syncservices/local/ folder that you had earlier backed up.
Hopefully the above method will work for you. However there is a slight risk that syncing may delete the data from your iPhone, +so proceed at your own risk+!
I hope this helps...
Many thanks to all of you who wrote to help me.