I cannot sync my 1.1.1 iPhone anymore, I always get "iTunes could not connect to the iPhone "****" because an unknown error occurred (0xE8000024).

I couldn't find any information on my error, except on 0xE8000025:

I was cleaning up address book entries and one potential reason that I can think of is that I set "My Card" to an entry that contains umlauts. I have fixed that since, but now I seem to be stuck in some weird state.

I have already tried to erase all settings and data on my iphone, but that didn't fix it.

I also tried:
- Erase all information in ~/Library/Application Support/Address Book (by first exporting everything to vcf, erasing everything, rebooting, and then reimporting). And also for iCal.
- Erased some files in ~/Library/Application Support/iSync directory
- Erased iTunes preferences in ~/Library/Preferences/ (same for iSync & Address Book)
- Followed by a reboot
But that didn't help either.

Any ideas how to fix that?