Can ping to win pc's and router but not Linux over vpn link.
 

I have successfully linked 3 offices via vpn using DLINK 804V Routers. I have a Suse Linux and Windows PC's in all the offices. If we just call my offices A, B and C for the sake of my question. A and B communicate 100% to all machines. C also communicates with everything to office A and B. However A and B can see everything in C with exception of the Suse Linux box. I am not even able to ping this machine from A or B. With office C being miles away I am praying that I don't have to make an unnecessary trip. (I have tried to access the Linux box using Putty via one of the Windows machines at office C however this seems to have it's own problem, because I can ping I believe it's unrelated) I do know that the Linux box at office C is otherwise working fully.
Is it the linux box which has not been changed that is at fault? Could it be the router? Both have been reset?
Thanks guys