ok, so i found a fix for this, but your probably not going to like it. i had the same problem with my 3g iphone, but the notes were not working as well. after searching the web for a while, i came to the conclusion that the notes file was corrupted. so i deleted it, restarted my iphone and they worked again. well, wasn't long before i began to realize that the address book files were also corrupted. so i had to delete that as well and let it make a brand new one.
basically what i am saying is, your address book is most likely corrupted in some way, and you are going to have to delete the file and let the iphone make a new one. to do this you can either
Option 1
SSH into "private/var/mobile/Library/AddressBook" and delete the "AddressBook.sqlitedb" file. hopefully you have a backup with an uncorrupted file with which you can restore it with. otherwise, your out of luck.
Option 2
install mobile terminal if you don't already have it. then type in
"cd /private/var/mobile/Library/AddressBook" and hit return. then type in "rm AddressBook.sqlitedb" and hit return.
notes:
1. your Iphone/Ipod touch must be jailbroken for either of these to work
2. you must restart your iphone/Ipod touch after both methods before any affect will be noticed.
3. you must have OpenSSH installed through cydia for method one to work
4. the second option is based on a method of deleting the notes file, and while it shouldn't be any different,
I guarantee nothing.
links:
SSH program for windows:
click here
SSH setup for Mac:
click here
other:
if you have any trouble with anything feel free to PM me or just search google. there are plenty of forums with help topics on these programs.