I am presently working with IBM to try and resolve an issue which may be the same, or similar, to yours. We have several people in our organization experiencing freezing up of their calendars upon sending or receiving meeting invitations. We are using ver 7.0.3 as well. Our clients are using the multi-version install as a lot of the PC's are used by a number of people (different shifts, etc). I have deleted and reinstalled Notes and it may seem to solve the problem but, eventually, it comes back. Meeting invitation can be from any person at any time and clicking on any meeting invitation could start the freezing process. If you have had any luck in resolving your issue, please let me know.