Linksys wrt54G with sveasoft Alchemy-pre5_4a firmware

Hello folks,

I have a linksys wrt54g routing and ap-ing. (with a speedtouch 510 adsl
modem, nat spoofing). All works fine, Except some websites will not open. It
will connect, but after a while the connection times out.
Other sites open normally.
When i ping the site by url, i can see the ip-nr, so i guess its not a dns
problem.
When connecting through the speedtouch alone, they open fine so i thing the
problem is in the linksys (sveasoft)
I connect to the linksys by wired lan.

Anyone any ideas?

Harry