I have same problem but don't have extended search installed. This error started after I did sync with Mac Address Book. There were some conflicts, and I updated from Mac. I think the problem may be because of the labels in fields got changed (?).

Having read this I installed extended search, rebooted, uninstalled, rebooted, and all ok again. Maybe installing and uninstalling it cleaned up the contacts file? Anyhow it worked as a fix.