iCal event editing problems?

Since upgrading my OS I cannot edit the event headings in iCal. I can open my events, new or existing, I can select the edit window, but as soon as I click on the heading in the edit box to make a change the edit box turns into a get info box. The heading wont highlight for me to make a change. It will let me edit all the other info in the event box but not the heading.

I have completely trashed iCal, including the cache files, on numerous occasions and fre-installed from my install disks with no luck. The funny thing is the same iCal calendar is running on my MacBook without a hitch. I have a feeling this problem is not actually an iCal problem but maybe a font or user permission problem.

Can anyone help, its driving me nuts.

I work on a Intel MacPro running 10.6.8 ( the latest upgrade.)