Using NetMon3 in Vista(x64), the error above (Unknown Error) dialog appeares. I just installed NetMon3 and clicked "New Capture" button and click Start to capture. Machine Environment: Using IPv4 and IPv6 Networks. I cannot see any NetWork in "Select Network" tab. NetMonInstaller was for x64. Please let me know how to start capturing correctly, or any infomation that might bother showing Networks! (I suppose no Network is shown in the tab concerned to the issue.) If you need any more infomation,please ask me.

Hi, Are you using Netmon 3.1? If not, please install the Netmon version 3.1and check the result. http://support.microsoft.com/kb/933741 If you are using Netmon 3.1, please run the program as administrator by using the following steps: Right click the Netmon 3.1 icon, and select Run as Administrator. If the issue persists, please capture a screenshot of the error message for further research. I look forward to your response.

Thank you very much!! It worked well. I'm using Netmon 3.1, so I tried the latter suggestion ( Run as Administrator ). And now I can see the Network Names in [Select Networks] taband can capture packets. Thank you for your advise!!

Glad to hear that.