OK folks, I think I figured it out!
Sometimes writing good thorough code makes things break!
The problem was that I was calling "GetCommProperties" on the port to find out if its properties are within acceptable contraints (baud rate, rx queue, etc).
The GetCommProperties on an XPort fails.
I commented out that call and everything seems to work fine now!
Please give my v0.6 test app a try at the "Releases" page of:
http://workspaces.gotdotnet.com/CFMapPoint
Please let me know if it:
1) finds your COM port
2) can open your COM port
3) can read GPS info from your COM port
If all looks good I will add this code to CFMapPoint hopefully this weekend.
Pv