In the past, old pc, old configuration all works perfectly. but now...
I have a strange problem, and I don't know if may be a firewall problem.
I have the PC with:
1 Ethernet interface
1 hamachi interface

Port 80 running httport
Port 21 running serv-u ftp server
Other port run other service.

The pc is connected to internet by the router adsl, and port 80 and 21 are forwarded virtual server. (the router configuration it's right I use it from two years, before I have this problem, without change configuration.)

Some times the application on port 80 (httport) and port 21 (ftp server) stop working on the Ethernet interface from internet.
That services still working over Hamachi and over LAN.
But if I try to connect from internet doesn't work.
So:
connect from Internet to port 80 or 21 doesn't work
connect from LAN to port 80 or 21 work
connect from Hamachi to port 80 or 21 work

I have try to restart router to solve but the problem persist.
I have try to disable firewall (it's really disable?) the problem persist.
I have close the application or stop the service and restart and them works again over internet. Over LAN and over Hamachi works always perfectly.

Any idea?