PC has "Internet Access" but cannot connect to the internet

Hi All

I have a strange problem. I have 2 PC's on a LAN, both Windows 7 Ultimate. Both PC's is connected to the same router via ethernet. Now PC number two has internet access and works great, but PC number 1 also shows "Internet Access" in the system tray and also in the network map, it shows that it is connected to the internet. But when I open ANY browser(FF, IE, Chrome) it cannot connect to the internet. Skype also cannot connect. As I said, the other PC (PC2) can connect fine and has the exact same setup as PC1. However, on PC1, when I manually connect via a dial-up broadband connection using the SAME username and password to my ISP as I used in the router config, it connects. The problem is that it loses the connection every 2 minutes or so...(failed to connect...redialing...). Can anyone tell me what I can do on PC1 to make it connect to the internet via the router the same way the other PC does?

Also, the two PC connects fine over the LAN between each other, but as I said, PC 1 cannot connect to the WAN the same way PC2 does.

Things I tried: I did a TCP/IP stack repair and rebooted. Nothing. I disconnected the 'working PC' from the LAN, nothing. I uninstalled the Antivirus and Firewall, nothing...

Router: Siemens Giga 762SX
Network adapter on PC1: Realtek RTL8139/810x Family Fast Ethernet NIC. I do have the latest drivers installed

Thanks

found the problem...It was the Firewall on the router, for some reason it only blocked the 1LAn connection, and not the other one. How do I allow that one PC connection through other firewall? I tried different ports but it keeps blocking the one PC only

First lets confirm it is the router firewall please turn off router firewall are you then able to connect to internet with both pcs to the internet?

Yes, indeed it is. Firewall on router off, both PC's now can browse the internet. Thanks

Ok that has confirmed the firewall seems to be blocking.

Now i would check the settings for the firewall and see if it has any restrictions in place for the affected computers mac address of pc1 and it's ip address.

The router firewall gives protection at the gateway so it would be in your best interests to check any settings in your siemens router and be able to re-enable the firewall for protection.