That's not totally true. I can delete entries in my phone address book, but I can't add them. When I try, I get a message that an error occurred and the entry is not added. This happens whether I am synchronizing or adding in the address book section.
I'm running Vista and MPT is the current version. At least it says it is when it checks for updates. I can't find a place where it says the version number.
A little more info. I uninstalled mpt, reinstalled, and during the install, it went online and updated from 4.36 to 4.51c. I can add calendar entries, I can delete phonebook entries from the phone, but I can't add them.