PC can "see" other PCs on network, cannot get online

We have a home network with 2 wired PCs, 1 wireless laptop+1 access point, and 4-port router. I turned on my home office PC this morning and could not get online (Internet Explorer) even though I could get to shared files on both of the other computers. How do I figure out where the problem is? Everything was working fine yesterday.
Thanks.

 

Down Load this little util (If you have a software Firewall temp disable it), http://www.keir.net/download/ip2.zip

This util would show you your local IP and the external Internet IP.

If you do not have local IP then you have to check your Network (see at the end).

If you have a Local IP and No Internet IP, you lost your Internet connection. Might be the Router (log to the menu system and check) or some trouble concerning your Internet service (call the ISP).

In case, you need to debug the Network.
In General, you can debug the Network Setting of the computer following these steps.

Step One. Check the Network parameters in the Computer's Device Manager. Make sure that the drivers are installed correctly; there is No IRQ conflict, and No Ghost installation. http://www.ezlan.net/faq#ghost

Step Two Verify Basic network setting in the OS: http://www.ezlan.net/Installing#verify
If the above two Steps indicates that every thing looks good but functionally it does not work.

Step Three. Check (and repair if necessary) the Socket Layers, Winsock, and or refresh the TCP/IP Stack. http://www.ezlan.net/clean#refreshnet

If need to Reinstall; Log to this page it have a lot of links to instructions for Windows Network Installation - http://www.ezlan.net/Installing.html

 

Thanks for your reply.

I downloaded the utility to show my local IP and Internet IP. Both are there.
I am able to ping the router.
I can access the internet from my other two computers and can share files back and forth with the faulty one.
When I look at my Device Mgr, everything appears to be okay. (I do not see any ghost inst)
In checking the Network Adapters I get a message that they are working properly.
You lost me on checking the socket layers, winsock, etc. I downloaded the WinSock fix and started to run it, but I got errors when I tried to do the registry backup before running it.
So here I'm stuck.

 

Sounds like your router isn't online! Log into the configuration of your router and check to see if it is. It could also be a DNS issue. See if you can ping google.com, and what type or response you get. See what happens when you ping 4.2.2.2. If you're still stuck, provide ALL the information you obtained by pinging and logging into your router.

 

I just discovered something really strange. I have not changed any of my security settings in Norton, but when cat5e had me disable my software firewall, I just realized that with it disabled I am to get online.
I checked the configuration in Norton and it had changed the Program Control for Internet Explorer to "Block". Is there some kind of spyware or something that would cause that? I just went thru extensive cleaning of our computers to rid ourselves of malware with chaslang's help.
Thanks for any insight.