lol Barto, your software firewall (assuming that you use one, even the Windows Firewall counts) may have had it's list of Allowed and Disallowed Programs reset or deleted by accident.
If not, and you are hosting from the DMZ, your network address may have changed so that your address no longer corresponds with the one that your router has set. Try Start -> Run -> "ipconfig" -> Make note of the IPv4 address, now open your router settings and look in any of the advanced tools section, or something similar, for the DMZ setting. Now compare the number IP of the DMZ computer with the one in the "ipconfig" prompt. If these do not match, then replace the address in the router settings with the one that "ipconfig" gives you. You should now be able to host any server you want. Another source of this problem may be the schedule that determines when these ports open and close, make sure that this is automatically adjusted for DST, and change the times accordingly.
