problem with openvpn

[Jesus arteche <chechu.linux@gmail.com>]

Hello,

I have  a debian lenny server for making service test. It has running a postfix+dovecot+amavis+clamav+spamassasin--> mail server. This service works perfectly. The problem comes when I installed a openvpn server. It works perfectly too with the clients. But sometimes it still working right with all services except when I try to connect by ssh, It holds in password or sometimes it just try to make the ssh connections until a timeout that it stop. if i make a ping it answers right. I got solved it by making a /etc/init.d/networkig restart. 
Someone knows how can I solve it without stoping network and starting again?

Thanks