OK here goes, been troubleshooting this for weeks now and still no closer to root cause other than i know its something _link_ed to Vista I have Vista ultimate running on my pc, the network its on comprises machines with a range of Os'es on including Linux, SBS, Windows XP and a laptop running Vista ultimate and on network via WLAN, remainder are standard wired lan connections This PC used to have windows XP Pro on and worked 100%, i wiped it and installed Vista and that's where the problems started. I get intermittent complete loss of internet connectivity and the only way to restore it quickly is to reboot the pc which is frustrating as it can happen a couple of times a day and i use this PC for business use and it will have around 15-20 windows open at any one time browsing, email etc etc The symptoms are as follows: using internet normally and then suddenly refresh browser / go to new page / open a fresh browser and get the standard IE browser error message as follows: Internet Explorer cannot display the webpage Most likely causes: You are not connected to the Internet. The website is encountering problems. There might be a typing error in the address. What you can try: Diagnose Connection Problems   More information I cannot even access anything running on port 80 on my own internal network either. Its like something has just suddenly killed port 80 if i try and access something like my router via a web browser i get the following: telnet 192.168.1.1 80 Connecting To 192.168.1.1...Could not open connection to the host, on port 80: Connect failed the strange thing is if any SSH / Streaming web radio _link_s are open these continue to function briefly as does a msn messenger conversation but eventually these die off as well here is ipconfig / all result with some info blanked out: Host Name . . . . . . . . . . . . : mypc Primary Dns Suffix  . . . . . . . : mynetwork Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : mynetwork Ethernet adapter Local Area Connection 2: Connection-specific DNS Suffix  . : mynetwork De_script_ion . . . . . . . . . . . : D-_link_ DGE-530T Gigabit Ethernet Adapter Physical Address. . . . . . . . . : 00-1B-11-0F-4E-F6 DHCP Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes _link_-local IPv6 Address . . . . . : fe80::ed8b:f03f:7f0c:bb9a%12(Preferred) IPv4 Address. . . . . . . . . . . : 192.168.1.17(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.255.0 Lease Obtained. . . . . . . . . . : 26 January 2008 09:41:36 Lease Expires . . . . . . . . . . : 03 February 2008 09:41:42 Default Gateway . . . . . . . . . : 192.168.1.1 DHCP Server . . . . . . . . . . . : 192.168.1.2 DHCPv6 IAID . . . . . . . . . . . : 268442385 DNS Servers . . . . . . . . . . . : 192.168.1.2 Primary WINS Server . . . . . . . : 192.168.1.2 NetBIOS over Tcpip. . . . . . . . : Enabled Tunnel adapter Local Area Connection* 6: Media State . . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix  . : De_script_ion . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface Physical Address. . . . . . . . . : 02-00-54-55-4E-01 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes Tunnel adapter Local Area Connection* 7: Connection-specific DNS Suffix  . : mynetwork De_script_ion . . . . . . . . . . . : isatap.mynetwork Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0 DHCP Enabled. . . . . . . . . . . : No Autoconfiguration Enabled . . . . : Yes _link_-local IPv6 Address . . . . . : fe80::5efe:192.168.1.17%13(Preferred) Default Gateway . . . . . . . . . : DNS Servers . . . . . . . . . . . : 192.168.1.2 NetBIOS over Tcpip. . . . . . . . : Disabled I can ping my default gateway and internet IPs whilst the browser cannot access sites, i can also do nameserver lookups I have done all the fault finding steps i have found online pertaining to similar faults as follows Disabled auto scaling (_script_ed to run after each reboot) Unticked IPv6 Unticked Computer can turn off this device in Nic config I have even gone so far as to swap out the NIC in the PC and also swap out router for different manufacturer models UpnP is disabled on router I have uninstalled any AV/FW Apps Disabled windows FW The really weird thing is, if i close down some of the windows and leave the pc alone for hours, i come back and sometimes the net is working again I should add that when my pc cant access the net, the remaining pcs / servers on the network can still access it fine as can my other vista laptop (via wlan) it's soooo frustrating, please help !!!

the ip address of 192.168.1.2 is an internal windows sbs server running lan dns and dhcp I have tried with and without Upnp before

I'm experiencing this same issue.  Here's an oddity.  I'm using microsoft VPC and my virtual machines can access the network even after the host computer (VISTA ULTIMATE x32). looses connectivity.  But only if they were booted before the host computer lost connectivity.  This is a very annoying problem and I've been fighting it for about 3 weeks now. It's very hard to troubleshoot because of the intermitant behavior.  I will definatly post any insite I gain to this thread, I'll also be keeping an eye here incase you make progress.  Good Luck!

well i am glad it isnt just me lol This damn problem is sooo frustrating as i consider myself fairly techy, at first i thought it was something simple, but the more i look into it the more it looks like a vista inherrent bug of some de_script_ion, something else i have thought about is that it might be _link_ed to bandwidth usage as if i am listening to streaming radio online whilst doing heavy updates of my websites then it appears to kick in earlier, Have you ever noticed similar ?

well this problem is really tiresome, its happening still once or twice per day I cannot get any help from MS as its an OEM license on a PC I built myself !! Any ideas anyone out there ?