We had a problem where we could not access one of our networked computers via the network - it was not visible or accessible. We instinctively suspected the anti virus, so disabled all of McAfee's security processes and found we could connect.
After some fiddling we isolated the problem to, as suspected, the firewall settings. When you try to turn off McAfee's firewall security process it frequently shows messages saying that you should re-enable it. Here is how to disable McAfee's firewall control and stop it from alerting you that it is turned off:
(McAfee Security Centre version 9.15, McAfee Personal Firewall version 10.15)
Now McAfee Windows Firewall Control is switched off, it will keep telling alerting you of this fact and ask you to turn it back on. To stop it from showing you these alerts, follow these steps:
Now you can manage the Windows Firewall yourself and it should be easier to find out exactly why you were having network connectivity problems in the first place.
Now try accessing your networked computer. If it still does not work, try switching off your firewall altogether temporarily. If this fixes the issue, go through your firewall's inbound connection rules. If it does not fix the issue it is likely that one of your computer's network and sharing settings are incorrectly set up.