Thanks Bob for your help. However administrator rights are not the problem.
I Googled a little bit (should have started there) and found out that the
reason originates from installing Acronis True Image 11 on laptop 2.
The workaround: use regedit and create a new key "IRPStackSize" with a value
18 or higher in
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic es\LanmanServer\Parameters
No wonder I could't solve it myself

)
BTW this can also happen with some Anti-Virus softs.
================================================== ================================================== ==
"Robert L. (MS-MVP)" <> a écrit dans le message de
news:
...
> If you logon both computers using the same administrator account with the
> same password, can you access it?
>
> --
> Bob Lin, MS-MVP, MCSE & CNE
> Networking, Internet, Routing, VPN Troubleshooting on
> http://www.ChicagoTech.net
> How to Setup Windows, Network, VPN & Remote Access on
> http://www.HowToNetworking.com
> "Gilles Garrigues" <> wrote in message
> news:4837cbf5$0$924$...
>> Here is my problem.
>>
>> I have a local network (Netgear router) under WinXP SP2 with 2 desktops
>> and 2 laptops (Wi-Fi connection).Each one has a shared folder for
>> communication. They all access internet without a problem BUT:
>> The 2 desktops and one laptop communicate between themselves without any
>> problem.
>> The 2. laptop can receive shared data from the 3 other computers but the
>> 3 other computers CANNOT access shared data located on the 2. laptop. The
>> error message says (in french) something like:
>> \\laptop2\tranfer is not accessible. You may not have the necessary
>> rights to access this network ressource. Contact your administrator...
>> Not enough memory on the serveur to handle that command".
>>
>> This used to work like a charm for the past 2 years. What the hell is
>> happening ?
>>
>> Thanks in advance for any help.
>>
>