Hi,
Try this and see if it solves the problem. Download the mojoportal-2-3-0-1-pgsqlreleasefiles.zip (the pgsql version for windows not mono). Grab the mojoPortal.Data.dll file from the/bin folder in that zip and paste it in the /bin folder of your installation, replacing the existing one.
Let me know if that solves it or not.
Thanks,
Joe