Need help with client site connectivity

Hello everyone, I'm having a small problem with
one of our branch offices. Here is the setup:
-We recently purchased dedicated connections to our branch offices from our ISP.

-4 out of 5 sites are working.

-At the 5th site we can browse the internet (port 80), send/receive email (SMTP and POP3) and ping other PC's at the main office (ICMP).

-However, the PC cannot browse network shares, nor can it connect to over Terminal Services Severs via Remote Desktop Client.

-Our router/firewall on the perimeter of the main office network was configured with all of the necessary static routes.

-If I use tracert from the PC at the 5th site, it reaches as far as the ISP's router at that site. The rest of the hops time out, but I can still ping PC's at the main office.

-I don't think its the firewall because the other 4 sites are working properly with the same setup.

Does anyone out there have any ideas/suggestions? Btw we already tried changing the PC and it still didn't work