I had my calendar go into a spin cycle again yesterday on my Samsung Galaxy S with 2.3.3.
I tried my previous "fix" (of clearing Email application data and re-setting up the account) but it didn't work.
As luck would have it, when I was troubleshooting I noticed a colleagues phone had also started doing the same.
I realized I had made a change to my contact (in a shared folder) to troubleshoot an issue for an iPhone user (reported on the sourceforge site) - I had added my birthday.
From what I can see, this causes the phone's calendar to think it has an appointment that the server does not have, so it keeps trying to sync to resolve the conflict.
I edited my contact record on the server and removed the birthday, and both phones returned to synching properly.
Thinking back, I had removed both my birthday and anniversary from my contact record at approximately the same time as I had cleared the data the previous time. I had forgotten about it until now.
So, I am really curious to see if any of you who are experiencing constant calendar synching have contact records with birthday's set - and if you do and you remove them if it solves your problem.
Note: The anniversary field does not cause the problem
Note: The birthday field had no ill affects on my Nokia or my WM phone. The birthday synced correctly to both.