internet not working with arjan's 2.6 testkernels

[Tim Kossack]

i'm using the arjan (hope that's spelled right) testkernels with rh9/xd2
on my sony pcg-z600lek notebook, but all kernels newer than
2.6.0-0.test5.1.36 seems to have problems connecting to the
internet. my notebook is connected to a sitecom-router, and in this way
(plus another switch connected to the sitecom-router) also to 6 or 7
windows-pcs. interestingly, i can connect to them via smb/nautilus and
can copy files from them to my pc with the new(est) testkernel running,
but when i want to fetch my mails via evolution or to browse with
galeon, the resp. program tries to connect, but there seems to be simply
no data coming. after a while, in galeon, i get the
"timelimit"-error-message.
note that when booting, i get the green "ok-message" for eth0 and again,
i can copy files from other computers in my network flawlessly...
my notebook's built-in network-adapter is a widely used intel
(pro?)-chipset (sorry for not knowing the exact type, if needed, i'll
try to find out the exact type).

so my question-is this a known thing, and is it fixable from my side-or
a bug in the (newer) kernels? 

thanks for any help!