Internet connection sharing

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hi, i am having some problems with the internet connection sharing, i have a DSL modem, i am sharing internet with 3 other computers on my network, the thing is that on 2 computers i cant see some internet pages, for example

http://www.terra.com.mx,

or

http://www.yahoo.com,

and on the third computer and the one that is the host i have no problems seeing this pages, please!! i need help,

Thank you,

JoSe