The Sacred Rules of Network Troubleshooting
1) The device isn't wrong. You are.
2) Plug the device in.
3) If you have made more than one change you have not identified the problem.
4) If nothing has changed, it isn't broken.
5) If it isn't a simple solution, it isn't fixed.
6) Don't rush.
7) What was the last thing you did before it broke?
8) If you are the only one having the problem, it IS just you.
9) Check the gateway. Ping something OFF of the subnet.
10) Are there any updates for the thing that isn't working?
Reposted from here: The Sacred Rules of Network Troubleshooting
The author also has a build of the SNMP tools for Windows as the makers don't provide a compiled windows version: net-snmp tools for windows (unofficial)