Open CPN no GPS position after upgrading to Lion.

[riddon]

Since upgrading my Macbook to Lion then Mountain Lion, I am no longer seeing a GPS position on Open CPN. I have downloaded what I think is the latest driver for the Prolific 2303 serial adaptor. When I use the command 'ls /dev/tty.*' in the terminal window it reports seeing the adaptor but I am not getting my boats GPS position. I am getting other ships positions with the AIS and everything else seems fine.

Any suggestions?