Contacts Map Help
 

I just got a contact on my map some 15km away doing 5knts, I plot a course to intercept. As I move towards it I click on the contact the the distance drops ( as it should do ) I get to 900mts no fog (my HD5770 1gb ddr5 produces fog in the game ) nothing to be seen and no sound contacts ? I listened myself. I plotted a course beyone the map contact and as I sailed away the distance got greater and turned around and sailed down the contacts given route and getting to within 500mts of the contact it was still showing 500mts and doing 5knts, I seen and heard nothing !

Anyone else get these types of map contacts ?