Lion Address Book problem - all of over 2,000 contacts disappeared - one mysteriously reappeared - then they all reappeared during resync with Gmail!

Question

The subject iine pretty much describes what happened.
I am wondering if it is anything to do with what looks like an odd file in the directory ~ Library -> Application Support -> Address Book
As well as the "real" database file there is this zero bytes one:
AddressBook-v22.abcddb.0F392545-78F2-4AE6-8D30-457C138332B2.unknown
From the date, it might be something to do with installing and linking Cobook to Address Book maybe?
These are the files and folders in that directory (sub-directory files not shown):
I have enabled the debug menu in Address Book but have not been able to find any info about how to use it.  I lie!  I did read that I might possibly have been able to "retrieve" the contacts using the debug menu "Force Refresh" - however that was after I had started to resync with Gmail contacts.
I realised that something odd was going on during resync when I saw that there were over 4,000 contacts being processed rather than the 2,000 or so that I was expecting.  Initially, none of the contacts groups from Gmail were showing in Address Book after this partial sync (I stopped it when I saw what was happening).  However, after quitting and restarting Address Book, the groups appeared again.
I have not lost my contact data - as well as Gmail contacts I also have an Address Book backup from about two weeks ago and also the backup created by Cobook about two weeks ago.  (Installed Cobook as it looked like a very efficient way of getting to view individual contacts quickly - Quicksilver just isn't finding them at all).  I used third party app "Contacts Sync for Google Gmail" to link Address Book with Gmail as it gives you options about what to do for each duplicate card that it identifies.
I then spent a lot of time sorting through the contacts on Address Book, finding duplicates, updating data, etc. with the intention of managing contacts in Address Book from then on, rather than in Gmail. Not all of these changes are reflected in the Cobook backup or Gmail.
My worry is, with Lion being such a god-awful Pig's Ear in so many more ways than this, that this Address Book mess might happen again.
I seem to have spent most of my time over the last month wrestling with the numerous problems that keep cropping up with Lion and getting little to show for it. 
WARNING! FOOT-STAMPING WHINGE ABOUT LION - LOOK AWAY AND DOWN TO THE HOWLING FACES - IT WON'T BE ANYTHING THAT YOU HAVEN'T HEARD BEFORE:
I gave up on OSX when I tried Panther - that was dreadful - but was lured back by Tiger, have used Leopard very comfortably for about 5 years, had a very happy couple of months with Snow Leopard and now - this mess that is Lion!  I have repaired OSX install permissions and "home user" permissions time and again, TinkerTooled it until I am blue in the face and it seems that every few days I manage to fix something and then almost immediately something else screws up. I can't upgrade to Mountain Lion on this machine and am seriously considering installing or running Linux as these problems with Lion are just never-ending - and then there are all the other stupid changes that have subsequently been sensibly reverted, mitigated or worked around in ML).
I have never bothered much with Address Book or Mail in the past as I have found them too limited.   I have used either the Gmail web interface or Thunderbird.  However, Gmail has started crashing my favourite browsers (Seamonkey and Firefox), Thunderbird has got just a bit too complicated and I cannot get Quicksilver to play ball with Gmail.  The Lion version of Address Book is better than Gmail Contacts and Mail Smart Folders can emulate Gmail filters and labels - a huge improvement.  So, just when these apps look good enough to be worth bothering with, they come part and parcel with what I have seen mocked, and rightly, as "Apple Vista"!
Sorry for that  but I am about at the end of my tether with it all ;-/
I would be very grateful if anyone can offer any advice about:
1) That strange looking zero bytes file in the Address Book folder.
2) Whether the Address Book debug menu options might be of any help in this situation?
There seem to be lots of people having problems with Address Book in both Lion and Mountain Lion, if not exactly this issue, so maybe the answers will help others too.
Fingers crossed!
Ms Mousette
ps. In the product list to tick for this question they are grouped so I cannot specify that this is actually nothing to do with the iPhone.  I have got a load of contacts on my iPhone too but I am not going to sync them until I have got this issue sorted out.

Answer 1

Could this font be the cause of the problem?
Possibly, since that font is not the one that Address Book uses and there is no method to specify or change the font used by Address Book. You could have recovered your Address Book contacts without syncing, so that could also be part of the problem. You should always make a keep a backup of your Address Book on your computer and in another safe location whenever you make any change to it.
May I ask why you haven't updated to 10.4.11 yet, as it provides various bug fixes and security enhancements?
Mulder