after a quick search i found the below
> goto the Sat Nav Menu main menu (destination screen),
> scroll down until you see information
> select position input
> enter the city
> enter the street
> select junction ?
> enter a crossing intersection road / street
> select the new menu option underneath Crossing the Junction
or
to find the almanac, park the car someplace with a clear view of the sky for about 15 minutes, you can check to see if almanac is found by going to the setting menu on the nav screen, and then pressing and holding the MENU button on the car. a secret menu will display and then you go to GPS and then I believe it is either status or tracking, but it will say ALMANAC and then YES or NO. If it is NO, then leave the car running outside until it switches to yes.
and if that dont work then...
Download Almanac
If the GPS almanac is not loaded, the nav is using default orbital data to determine what satellites should be visible. It can take longer to acquire a satellite fix when the almanac is not loaded. Almanac is lost when battery disconnected, and loaded automatically as follows:
Park the car outside, with the tailgate closed so the GPS antenna is not obstructed. Wait around 10 to 15min for the GPS almanac to be updated. You can observe the Almanac status in the service mode by selecting GPS, then Functions then GPS-Tracking info.
Calibrate Gyro Compass
The ignition should be in position 0 (off) during removal and replacement of the nav unit. After installing, close all doors, sunroof, bonnet and tailgate. A bus line reset will be carried out within two minutes. Resetting allows the gyro to perform a calibration run. Do not move or bump the car during this reset / calibration period. After a few minutes the calibration will be complete
another option is to disconnect your cars battery for 15 minutes