I'm not sure... But if you have an older backup, you can try to restore that backup. If that works, then probably the backup file is corrupted.
The other possible way is to try restore the backup file manually. The file which is named with extension .contact is actually a tar.gz archive, you can extract it in the phone itself (rename the files to end with .tar.gz and extract it from file manager, or by telnet using tar command) or by using separate tools in PC, such as 7zip archiver.
After this you will get a folder structur like below:
/contact
/email
/mms
/sysDatabase
Copy the sysDatabase folder and replace the folder in /ezx_user/sysDatabase. Reboot your phone and see if it is running or not.
Btw, the backup files is stored in /mmc/mmca1/KgApps/BackupTools/MyBackupFiles.