What could prevent a ping from being sent between the workstations when they are directly connected?

Question

What could prevent a ping from being sent between the workstations when they are directly connected?

Answer 1

within the directly connected networking world, using the wrong cable (using a straight through instead of a cross-over) cable would be one cause.  Windows has firewalls that might also cause the ping to fail.  Also, internet security software like McAfee or Norton Antivirus are also typically causes for this.

Answer 2

A rule in one machine's firewall that prevents pings (probably incoming) would do that.

Hope that helps.