i had a user at home install sp3 on their home pc, 100% legal version and now they cant connect to their home pc via RDC. however, another pc at the same home, has sp2 and we can connect to that one, from our office right now, with no problems.
i helped them configure both PCs and their router and both PCs were working before sp3 install.
i already had them check to make sure the firewall is off and it is, and i statically assigned both computers for them, so it isn't a problem with a wrong IP address or the router with the wrong ports being forwarded.
i changed the registry values on the computer that works so that it is using 3390 as the listening port. again, that computer, with sp2 is fine.
the computer with sp3 was left to 3389, the default value and we are having trouble connecting to it.