To rephrase what I think you're saying: You can ping Server A and Server B from any PC, but you can't ping Server A from Server B. Is that correct?
If so, there's nothing in a switched network that could cause your problem. However, you may have firewalls running on one or more of your servers which are blocking one or more of the IP addresses (maybe a range of addresses) in your network. They could be completely blocking the addresses, or just ICMP messages. What operating systems are involved?
Ed