This seems like a similar problem to the one above. I had navagation working fine just a few days ago and then out of no where whenever I click on navagation i get the error "parameter is incorrect" with an ok on the message. I can click ok as many times as I want but the message will not go away. I have to <ctrl> <alt> <del> to close street deck. I had this exact problem about a month ago and finally reformatted the hd. I could not fix the problem after uninstalling both street deck and map point and deleting all directories and searching through registry and removing any entries that seemed related. and the error never went away. I will try the fix for the problem mentioned above and post my findings.