Had the same problem with not working phone/contacts, freezing like "process com.android.phone - Force Close" etc.
I realized the error happens only after upgrading for example to KG, than after a short period making a backup of the whole system, downgrading to KF, then restoring with Titanium Backup.
It restores the whole system, including settings, and accounts and so on. This might be the problem. It seems nobody realized that the MODEM and PHONE is upgraded too, so there might be some components not compatible with earlier versions.
Solution: restore only user apps & data, not the system settings. Use a separate app for SMS, call logs, contacts or calendar. Do a cache wipe and then a fact reset from MENU+UP+POWER (restore menu), then reinstall your choice of firmware, restore user apps&data with Titanium or anything preferred, then enter/restore everything else manually. No problem when upgrading.
Tested, had 3 sleepless nights, but works for me.