my 2 cents:
- see if chkdsk helps. Maybe some backup file used by itunes has issues.
- try a different usb port to sync your iphone
- switch to icloud for the backup of your iphone
- reset the bios settings to default. Which BIOS version does you have DH67BL has? You can check the download section if a newer BIOS exists (the readme of every BIOS revision lists the issues resolved). From my personal experience I would be careful with a BIOS update as it sometimes introduces new problems and not all versions can be downgraded.