WAN and VPN access

[Malesefx]

Greetings,
I have Pfsense 2.0.1 , it was working fine but then VPN services stopped, then accessing from outside stopped.
When I restart, those services work for 2-3 minutes then it stops working.Even though accessing from outside or vpn doesnt work, it has full internet connectivity.

I checked the VPN logs, then I saw "No buffer space available", I read forum experiences about "ifconfig em3 down, ifconfig em3 up " I did that; It didnt work, changed WAN port from em3 to em2, it didnt work
I reinstalled the Pfsense from scratch, still having same problem

Next step, I am planning to change harddrive that PFsense installed, but I would love to hear your expertise if there is a work around to fix the issue

Thank you in advance