I have done various test with builds and I have noticed that once you have removed a rule that allowed RDP from XP to 2003, you won’t be able to replicate the rule again. Even if you try to repeat, you won’t be able to connect. Perhaps this may be a bug but I’m getting put off a bit by this now.
Did you reboot in between tests ?
I did test in between test. Some more tests I have carried out. I did a new build of win2k3 and installed comodo, enabled RDP and I was able to connect from XP. I did windows update and patched it up and as soon as I rebooted, I am not able to RDP again. Perhaps a bug with comodo somewhere. I have done this quite a few times and still the same!