I have the same problem. I dowloaded and ran Intellisync and set it up so it
syncs both ways.

The panel shows up : Confirm Appointments Changes and in the Details
everything seems ok.
After this I get this  error:

Some of the data you submitted was not valid and not entered. Please check
the object you created or modified. (this last line is almost illegible
because only the top of the letters show)

In my Outlook calendar nothing from the Hotmail calender is shown and now in
my Hotmail calendar  I have several instances of the holidays that I had in
Outlook

thanks

Joe