Intermittent "The page cannot be displayed" from IE but OE can still send/receive emails

A customer has a network of Win XP Home SP2 PCs all connected by wireless to
a BT1800 wireless router. One of the PCs (it's always the same PC)
intermittently cannot display web pages: it gets the standard "The page
cannot be displayed" / "Cannot find server or DNS Error" message. Typically
if he keeps retrying, IE springs back into life spontaneously after a few
attempts, then works flawlessly for a while before failing again.

However... the customer reports that even when IE has got into this state,
he can still send and receive email. This suggests that the problem is
apparently not simply due to temporary loss of wireless signal.

The only time that the fault occurred during the hour and half while I was
there, the whole wireless connection had dropped out - despite the wireless
icons still showing full signal strength, I couldn't ping the router or any
other PC on the LAN, never mind external web address that would have
required DNS.

If the customer is right that IE fails but OE continues to work, what could
be causing it? Could it be the router getting into a state where it won't
pass HTTP traffic to a specific PC even though it will pass SMTP or POP
traffic? When the fault occurs, other PCs can still access the web, so it's
not that the router is refusing to pass *all* HTTP traffic.

"Martin Underwood" <(E-Mail Removed)> wrote in message
news:4359753b$0$73614$(E-Mail Removed)...
>A customer has a network of Win XP Home SP2 PCs all connected by wireless
>to
> a BT1800 wireless router. One of the PCs (it's always the same PC)
> intermittently cannot display web pages: it gets the standard "The page
> cannot be displayed" / "Cannot find server or DNS Error" message.
> Typically
> if he keeps retrying, IE springs back into life spontaneously after a few
> attempts, then works flawlessly for a while before failing again.
>
> However... the customer reports that even when IE has got into this state,
> he can still send and receive email. This suggests that the problem is
> apparently not simply due to temporary loss of wireless signal.
>
> The only time that the fault occurred during the hour and half while I was
> there, the whole wireless connection had dropped out - despite the
> wireless
> icons still showing full signal strength, I couldn't ping the router or
> any
> other PC on the LAN, never mind external web address that would have
> required DNS.
>
> If the customer is right that IE fails but OE continues to work, what
> could
> be causing it? Could it be the router getting into a state where it won't
> pass HTTP traffic to a specific PC even though it will pass SMTP or POP
> traffic? When the fault occurs, other PCs can still access the web, so
> it's
> not that the router is refusing to pass *all* HTTP traffic.
>
sorry, i haven't got the answer but it could certainly happen that email
continues to work whilst web browsing is intermittent.
this is probably due to the fact that a dns server will have mail server
addresses more or less permanently cached, so a response comes quickly,
whereas random web addresses take (milliseconds) longer and time out.
there is a basic hardware problem here as well, isn't there? why does the
connection die rather than degrade?
i guess that if the wireless connection could be stabilised, the other
problem would go away.
is it possible to move the pc temporarily closer to the AP and see what
happens? or use a cable?
bob

check the MTU settings on the clients machine..

On Sat, 22 Oct 2005 00:09:22 +0100, "Martin Underwood" <(E-Mail Removed)>
wrote:

>A customer has a network of Win XP Home SP2 PCs all connected by wireless to
>a BT1800 wireless router. One of the PCs (it's always the same PC)
>intermittently cannot display web pages: it gets the standard "The page
>cannot be displayed" / "Cannot find server or DNS Error" message. Typically
>if he keeps retrying, IE springs back into life spontaneously after a few
>attempts, then works flawlessly for a while before failing again.
>
>However... the customer reports that even when IE has got into this state,
>he can still send and receive email. This suggests that the problem is
>apparently not simply due to temporary loss of wireless signal.
>
>The only time that the fault occurred during the hour and half while I was
>there, the whole wireless connection had dropped out - despite the wireless
>icons still showing full signal strength, I couldn't ping the router or any
>other PC on the LAN, never mind external web address that would have
>required DNS.
>
>If the customer is right that IE fails but OE continues to work, what could
>be causing it? Could it be the router getting into a state where it won't
>pass HTTP traffic to a specific PC even though it will pass SMTP or POP
>traffic? When the fault occurs, other PCs can still access the web, so it's
>not that the router is refusing to pass *all* HTTP traffic.
>
>

Firewalls such as the one in Norton Internet Security is notorious for
causing this problem. Firewalls (even the Windows Firewall) tend to
intermittently block a process called the Microsoft Generic Host
Process for Win32 Services. Change the firewall's setting from
'Automatic' to 'Permit All' or 'Always Allow', etc. - whichever
setting your firewall permits.

Webbie wrote in
(E-Mail Removed) om:

> Firewalls such as the one in Norton Internet Security is notorious for
> causing this problem. Firewalls (even the Windows Firewall) tend to
> intermittently block a process called the Microsoft Generic Host
> Process for Win32 Services. Change the firewall's setting from
> 'Automatic' to 'Permit All' or 'Always Allow', etc. - whichever
> setting your firewall permits.

Thanks. I'll check this. I'm trying to remember which firewall the customer
has. I think it may be McAfee. I'll check the list of permitted applications
and their settings. I'll also make sure that Windows Firewall isn't running
in addition to McAfee.

Someone earlier suggested that it happens more with web than email because
the ISP's email servers will be probably be permanently resident in their
DNS server whereas some obscure web address won't and will require a further
DNS lookup. However i) the problem only affects one PC, not another
identical one; ii) it happens even with the customer's home page of
www.google.com, which is almost certain to be cached at the ISP's DNS
server!