I recently changed the wifi channel on my router to 13 to minimise interference, this seemed to work giving a good signal on all PCs in the household except my daughter's laptop (I did not notice this as she was not using it for a few days).  When my daughter turned her laptop on it would not connect to the router / network / internet.  I checked everything, the network was simply not visible even though it was there on all 3 other PCs, eventually I remembered I had changed the channel a few days before so I changed it back to 11 and everything connected, changed it back to 13 again and my daughter's laptop disconnected again.
The Laptop is a UK spec. Acer Aspire 5720 with a Broadcom B43xx series internal wireless card (Wifi 'g'), running Vista home premium, fully updated.
I know only channels 1 to 11 are used in USA but 1 to 13 are ok in UK, I checked all localisation settings and reinstalled the wireless driver (from Acer website as I could not identify the correct one via Broadcom), still no luck.
In reading through the driver setup files I can find a list of channels 1 to 14 so I guess the card and driver should support channel 13.
I can work with channel 11 but I'd like to know why I can't use a channel that I should be able to.

Any suggestions will be appreciated, thanks in advance,
Alastair.

Channels 1, 6 and 11 give completely separated signals.
Even if you could use channel 14, it would overlap with channel 11 setups...
see http://en.wikipedia.org/wiki/List_of_WLAN_channels

Scan for the best channel to use before choosing.

On a scan I can normally see between 5 and 8 wireless networks, most using channels 1 & 6 (also one or two on 11 but these are the lowest signal levels of the visible networks)  but there is one which occasionally appears on channel 7.  I wanted to try channel 13 to completely avoid overlap with channels 1 to 8.  There is little, if any, problem from neighbouring networks but having tried a valid channel and found this problem I now want to find a solution.  There is always the possibility in the future that I would wish to connect to another network using this channel and the laptop should be able to do it.
In areas with many wireless networks it is impossible to completely avoid using overlapping channels, as you say channels 1, 6 & 11 do not overlap, another recomended setup is channels 1, 7 and 13 which separarates the channels a little more.

You might be better off with a higher-gain aerial, if you are suffering serious signal degradation.
This could either be on the AP or the PC (assuming the present aerial is removable)...

Thanks Axis,

Aerial on my Belkin router is firmly fixed to it, I don't really have interference issues, just wanted to optimise my wireless.

I'd still like to be able to use the Acer laptop on channel 13 if required, if only as a matter of principal as it is supposed to be UK specification and channel 13 is a valid UK channel.

-  Alastair.

Its a problem I come across on acers a lot of the time and the latest driver from acer doesnt usually sort it.  depending on the location of the mini pci/mini pci-e card swapping it for a different card might be possible.  I replaced the broadcom card in my dell with an intel a/b/g card recently and found it to give far better wireless performace.

Presumably Acer are frightened that you will use your PC in the USA (where channel 13 isn't allowed).

Also I have noticed that you cant use channels 12 & 13 on the intel 4965 a/b/g/n card incase you try one of those cards.

Thanks all for the further updates.

I also previously changed the card in my Dell (to Intel Pro for better Linux support), If I can find the 'spare' card I'll probably give that a go (can't remember if I ever tried ch13 on the old Dell card though).

Thanks again,  Alastair.