How did you install CNE?
If CNE installer gives you error you can just copy the gmap folder
Gmap folder path on pc:
WindowsXP:
C:\Documents and Settings\username\Application Data\GARMIN\Maps
Vista/Seven:
C:\Users\username\AppData\Roaming\GARMIN\Maps
No , first install CNE, or copy gmap folder,than run in the gmap folder the mapset unlocker I gave you the link above .

If Mapsource and Basecamp install. give you error there is something corrupt in your MS or BC installation , may be we could help you better if you shot a screen of this error or write it down exactly.