SQL SERVER Communication Link Failure

Hi, I work for a company with 16 offices connected by frame relay. They all use a MS SQL server (v8) based software named SOFTPRO.
Every none and then the users get the error “communication link failure” and get kicked out of the application. I am not a DBA, how can i takle this problem? another person have already spent 1 months trying to troubleshoot the problem, but he is a cisco certified and have only approach the problem by analyzing network traffic, sniffer, etc.

Any ideas?

Thanks