I am connected fine to the network, but I can't access computers outside the network.For example:"ping <other computer on network>" works fine, but "ping google.com" fails, saying that the host can't be found.Other computers on the network can access the Internet, it's just this one .I'm using Windows XP Home.Thanks in advance for the help.

HiMaybe this can Help, http://www.ezlan.net/debug.html Jack-MVP Windows Networking. WWW.EZLAN.NET

I tried what it said there; still not working.

I also tried system restore to a date before it stopped working, and that didn't help either.It stopped working after I tried some DNS Cache and QoS Bandwidth Reserve registry tweaks. It didn't start working again even after undoing the changes :(

What happens if you try to ping Google by its IP address instead of its name? (ie ping 66.102.7.99" )If that works, then you have a DNS problem. If it doesn't then you might have a routing or firewall problem.HTH, JW

I just tried that out, and it works! What should I do to fix the DNS problem? The HOSTS file looks normal, with just one entry for localhost. I also tried using OpenDNS, and that didn't help. Will I need to reinstall the OS?

I just tried that out, and it works! What should I do to fix the DNS problem? The HOSTS file looks normal, with just one entry for localhost. I also tried using OpenDNS, and that didn't help.

Since you've tried OpenDNS, I assume that when you type "ipconfig /all" in a command window, you get a valid DNS server's IP address listed on the DNS line.One possible problem is that a firewall is blocking your DNS queries. As a test, try temporarily disabling all the firewalls on your machine and see if that helps.A couple of free debug tools that sometimes work to fix similar problems are the following... It might be worth a try:LSPFix: < http://www.cexx.org/lspfix.htm >WinsockXPFix: < http://www.snapfiles.com/get/winsockxpfix.html >You might also try installing a packet-display program such as Wireshark , then execute a couple of "nslookup" commands to see if the DNS packets are getting out of your machine and answers coming back.HTH, JW

I tried nslookup, and it succeeds. LSPFix didn't detect any problems.What could be wrong?

HiTry again this process.Start an Admin Command prompt.Type netsh winsock reset in the Command Prompt , and then press the Enter key.Do the same processes for refreshing the TCP/IP just replace the typed command with.netsh int rese t press Enteripconfig /flushdns press EnterReboot---------------If this does not help, my guess would be that your tinkering with the Registry "trashed" the Network aspects of the OS beyond simple repair.That leaves you with two options.1. Backup data, applications etc., and do a fresh install of WinXP.2. Do an install refresh.With Win XP, you can do a refresh of the OS. It is like re-install but it leaves all the data, applications, and most configurations intact.Refresh XP Installation. Boot from the XP original CD. Skip the first screen that offers Console Repair, and continue as though you install a New XP.After you Agree etc., the new install screen will come on and would detect the current XP installation.Choose the Repair option by Pressing R for Repair.Use it, would take about 45Min. and you will have a Refreshed Installation of XP while keeping all your data and XP configuration.P.S. If you made changes to WinXP Security setting (Like Firewall special permission), you have to look over them after the refresh since they might revert to the Default. Jack-MVP Windows Networking. WWW.EZLAN.NET

That didn't fix it. I did an sfc scan, and there were a few errors in the event viewer. It said that some files like "oembios.bin" and "oembios" with some other extensions could not be repaired.If I reinstall, will it totally overwrite the registry, causing me to need to reinstall all of my programs?

HiIf you do refresh install as I mentioned in the end of my previous post, your data and applications should stay as is.However, make a backup before you do it, unforeseeable issues can always happen in a situation like this. Jack-MVP Windows Networking. WWW.EZLAN.NET