Access to certain web sites not possible

I have an MS broadband wireless network in place at home.
My wife accesses the wireless network through her laptop.
On the laptop, she cannot get access to certain web pages,
that are accessible from the machine connected to the
wireless router (i.e. the machine downstairs). I have
tried clearing the browser cache on the laptop, but it
still cannot access some sites. What could be causing
this problem?

If you have a PPPoE DSL broadband connection the problem
is MTU and RWIN.
>-----Original Message-----
>I have an MS broadband wireless network in place at
home.
>My wife accesses the wireless network through her
laptop.
>On the laptop, she cannot get access to certain web
pages,
>that are accessible from the machine connected to the
>wireless router (i.e. the machine downstairs). I have
>tried clearing the browser cache on the laptop, but it
>still cannot access some sites. What could be causing
>this problem?
>.
>

I have a Comcast broadband modem (not DSL). Also, on both
computers, I have Norton Internet Security installed, with
the firewall active on both machines. Do I really need a
firewall in both places? Could that be causing the
problem?

Thx
>-----Original Message-----
>If you have a PPPoE DSL broadband connection the problem
>is MTU and RWIN.
>>-----Original Message-----
>>I have an MS broadband wireless network in place at
>home.
>>My wife accesses the wireless network through her
>laptop.
>>On the laptop, she cannot get access to certain web
>pages,
>>that are accessible from the machine connected to the
>>wireless router (i.e. the machine downstairs). I have
>>tried clearing the browser cache on the laptop, but it
>>still cannot access some sites. What could be causing
>>this problem?
>>.
>>
>.
>