When looking at problems that you think might be network-related, ask yourself these questions:
Which processes usually retrieve a large amount of data?
Are a large number of network errors occurring?
What is the overall performance of the network?
What is the mix of transactions being performed using SQL and stored procedures?
Are a large number of processes using the two-phase commit protocol?
Are replication services being performed on the network?
How much of the network is being used by the operating system?