difficulty in sync

I have a 3GS which presently is at 4.3.2. It has never been jailbroken, never been tampered with. For the last couple OS upgrades, though, each time I upgrade, there has been a problem with the upgrade. I lose my entire Address Book on my Mac, only for it to appear days or weeks later, each time, with multiple duplications (just under 3,000 contacts becoming 68,000+ contacts).

I am now trying to upgrade to 4.3.3. I have not synched in a while, as I was trying to clean up the duplicates on the Mac and getting rid of some contacts I didn't need. I have clicked on replacing Contacts on the iPhone on the next sync. It keeps on getting hung up on the synchronising contacts stage. I really don't want to have to go through the experience of losing my AddressBook again.

Does anyone have a suggestion?

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Tired and frustrated, tempted to go back to a simple Nokia!