I have had this problem three times since installing Vista and the only solution I found so far was reformatting the entire computer:I have got Vista installed on a laptop, which connects via a wireless router to a small Office LAN (with one W2003 Server) and sometimes to my Home LAN (with one XP machine). This works absolutely fine for a while, but from one day to another I cannot see the other network computers by name anymore (I can still ping them). The only explanation I have is that I take my laptop sometimes to a client's office who has a network with a Proxy to which I connect. I noticed the last time the problem with my network visibility occured that it was a day after I went to see that client.I checked all the settings in Vista Network and Sharing Center and they look fine to me:Network Discovery: OnFile Sharing: OnPublic Folder sharing: OffPrinter Sharing: OffPassword protected sharing: OnMedia sharing: OffAll my computers have got the same Workgroup Name and I haven't made any changes to the XP machine or to the Windows 2003 server. One day it all runs fine, the next day it can't see any of the other machines anymore.Any ideas as to what could be causing this and how I can fix it? I am sick of reformatting my laptop every couple of weeks just to get the Network Visibility working again...

This behavior can be caused by the installed anti-virus and firewall. Please temporary disable the anti-virus and firewall, and click Start->Network to check if the issue still occurs. If the issue persists, please check if NetBIOS over TCP/IP is enabled. 1. Click "Start", input "NCPA.CPL" (without quotation marks) and press Enter.2. Right click on the connection that you use for the local connection, and then click "Properties". 3. Click Continue button to verify the administrator permission.4. Click to select "Internet Protocol Version 4 (TCP/IPv4)", and then click "Properties".5. Click "Advanced" button in the open window. On the "WINS" tab, click to select "Enable NetBIOS over TCP/IP", and then click "OK" to save the setting. Is the issue resolved? If it persists, please let me know if you can only see Windows Vista computers in the network, or all of the computers including Windows Vista computers are not listed. Hope it helps.