Force close usually comes when the app has gotten corrupted.
I am sorry but, you have got to perform a full wipe.

all of a sudden I get this message "Sorry, the process com.htc.calendar has stopped unexpectedly. Please Try Again, force close"

whenever I try to edit something in my calendar or to add a new item.

Verizon says to wipe the phone back to factory settings! don't want to do that. Eris works great otherwise and I don't want to have to reload apps, re set up email etc etc etc.

does anyone have any ideas on how to solve this problem? are there any apps that function as a fix utility for the calendar?

thanks