When i start with a clean calendar and an empty contacts list. Google calendar and contacts sync perfect. Changes made on google are also synced correctly.

I found out that if i add an postal code to an contact. The "exchange server not responding" error appears. Clean my calendar and do a re-sync. All is fine.

Guess there is something wrong with the way Maemo wants to sync certain fields. Because it cannot sync the "postal code" itreturns with a "exchange server not responding". I now have the postal code in the "region" field and it sync again!

I guess there are more fields who will give this error.