you'll have to wait for the next NAV DVD to be released, there is a problem with the 2006-02 disk. Someone contacted BMW about the postcode thing and the reply they got back was:

Dear XXXXX


BMW UK can confirm that due to a technical issue with the latest navigation disc (issue:2006-2) supplied by NAVTEQ, the option for postcode address entry has not been programmed correctly.

Therefore for version 2006-02 all navigation inputs will require to be entered via the full address mode.

This only affects vehicles equipped with Professional navigation on the CCC platform for the following model series:

E87 -BMW 1 Series
E90/E91/E92 -BMW 3 Series Saloon, Touring and forthcoming New 3 Series Coupé
E60/E61 -BMW 5 Series Saloon and Touring
E63/E64 -BMW 6 Series Coupé and Convertible

The fault has been located to an incorrect data file on the new navigation disc and the Factory is currently looking into possible solutions to overcome this issue.

We can confirm that every effort is underway to resolve this issue, and will be resolved in due course.

May we suggest you register your concern to our BMW Approved Dealership who in turn will be able to offer further assistance once details have been announced by our suppliers.

postcode search for London does still seem to work though!