This is a weird one:

After a year of problem free syncing with Activesync 3.7, suddenly a number
of Contacts (some 10%) fail to sync with an "unresolved" error. A long &
painful process of elimination suggests that this is a problem with Contacts
that have text entered into the Notes field within the Contact. I can create
a new Contact & populate all fields except Notes & the record will sync OK.
As soon as I add ANYTHING into the Notes field the Contact will not resolve.
Just deleting the text does not restore the Contact, the entire Contact has
to be deleted.

I have upgraded Activesync to 3.8, hard reset the iPaq & even tried a
different model of iPaq to no avail. All available Windows XP & Office
updates have also been applied. The iPaq currently in use is a 4150 with PPC
2003.