I asked this over at superuser but they weren't able to help, so I was hoping the sysadmins here will be able to advise as to what's wrong. Although the issue here is with a PC and not a server it still deals with networking so I hope it's not too irrelevant.

The Issue:

I have a desktop on which I cannot access Gmail and also youtube sign in (I believe since youtube is owned by google they both use the same sign in system).

On other computers that uses the same connection via a wireless router I can access both gmail and youtube sign in just fine. On this computer which doesn't have a wireless card and so I have to connect via Ethernet cable (connected to a USB converter since the Ethernet port doesn't work anymore) I can access all sites and services including things like aol and hotmail. But only when it comes to gmail, do I get complete and utter throttling. I even turned off my AV ad Firewall momentarily and no luck.

The gmail log in page starts to load and by mid point it just stays there loading and loading and loading... never ends.

I tried everything, I reset the modem and router multiple times. I reinstalled my operating system from a vista to a windows 7 hoping that a complete reinstall would solve the issue, but no luck.

And yes, I am going to call my ISP but not to solve this issue, but to cancel them. I want to upgrade to cable from DSL anyway. I didn't mention my ISP because I'm not sure if that is within the rules (if it's okay some one let me know and I will).

P.S. All this happened one day, before that gmail was perfectly accessible in this computer. I can't remember anything special happening on that day prior to this. The only thing I can think of is, my ISP or Google itself is blocking this computer based on it's mac address, but I don't know if that's even done.

Additional info:

PC: Windows 7 Ultimate 32 bit Connection Type: DSL Connecting Medium: Ethernet cable via USB converter

EDIT:

I should mention I can access gmail and youtube just fine through a IP proxy service.