I`m unable to access any web page using internet explorer, but I could browse with Firefox.

There could be many reasons for this. Lets check and resolve step by step.

Lets begin with winsock. I guess there may be a problem with your winsock.

METHOD - 1
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If you are running WINDOWS XP WITH SERVICE PACK 2 then try the following.

1. Click Start. Click Run. Type netsh winsock reset, and then click OK.
2. When the command prompt flashes, restart the computer.

Note:
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I suggest you to back up the keys before you continue. To back up the key, right-click the key and select Export. When you are prompted for a name, enter it and then save it. By default, it is saved in the My Documents folder. You can delete this file after you confirm that the system is working correctly.

METHOD - 2
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If you are NOT USING WINDOWS XP SERVICE PACK 2 try the following.

1. Click Start. Click Run. Type regedit, and then click OK.
2. In Registry Editor, locate the following keys:
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Winsock
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Winsock2
3. Right-click each key, and then click Delete.
4. When you are prompted to confirm the deletion, click Yes.
5. Restart the computer.

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Please revert back with your results. So that I can think of other options.