Assume there are 4 PCs in this network environment, 1st My pc Windows XP Pro SP2, 2nd Virtual PC host, 3rd Windows Vista Virtual Machine (Store in 2nd PC), 4th another user Windows XP. 1. The incident was that when I used my PC ping to Windows Vista Virtual Machine. Some times it respond, some times not. As well as when the 4th PC ping to Windows Vista Virtual Machine. Some times not respond. 2. I use my pc which Remote Desktop connection, once I cannot ping, I cannot establish connection. As far as now, i have investigate the network property use "netsh interface tcp set global". 3. I have modified the parameter "autotuninglevel" also "congestionprovider". But, now still not thing better. I ' m wonder which action should be taken in order to keep the network transaction stable. Or any property or services should be adjust. Thank you in advance for any suggestions.

Hi Chanavee, Thank you for the post. Regarding the Virtual PC-related issues, I suggest submitting them in our Virtual PC newsgroup. The support professionals there are better equipped to assist you. Thank you for your understanding and cooperation. For your reference, I've included the link of Virtual PC Newsgroup: http://www.microsoft.com/windows/products/winfamily/virtualpc/support.mspx http://www.microsoft.com/windowsxp/expertzone/newsgroups/reader.mspx?dg=microsoft.public.virtualpc&lang=en&cr=US In addition, you may capture the network packets on both machines to check if the ICMP packets are sent/received. Here is the steps for using Netmon on Windows Vista: ===================== Log on to the Windows Vista machine with the local Administrator account. Download the NetMon3.1 from the following link and install it on the machine:http://www.microsoft.com/downloads/details.aspx?FamilyID=18b1d59d-f4d8-4213-8d17-2f6dde7d7aac&DisplayLang=en When the issue occurs (The network connectivity status appears as Local only), right-click the Netmon icon and select Run as Administrator. In the Microsoft Network Monitor 3.1 window, click Create a new capture tab. In the new tab, select all the Network Adapters in the Select Networks window. After that, press F10 to start NetMon. Reproduce the issue. After that, please go back to the Netmon window and press F11 to stop the Netmon on the Windows Vista machine. Hope it helps. Sincerely, Joson Zhou Microsoft Online Community Support