I think this may be a KDE issue in 8.04 but I'll post anyway. Basically, when I boot up, I have no net access. If I do a (sudo) console I can ping anywhere. I just have no net access though the browser,however, if I pull up the network gui control and select my home profile (via authentication) things work just fine. I've created a /etc/rc.local script to do an ifdown/ifup...no joy, created a /etc/rcS.d/S99network script to do a /etc/init.d/networking restart along with chmod 700 /etc/rcS.d/S99network to see if that would work as I've done in other debian derivatives with success. But this is stubbornly refusing to remedy the problem. So, all I want is for the network to be up and ready when I boot into my user account.... should be easy but I'm stumped. Any takers?

wireless?
if so what card/chipset?

lan?
take a look at /etc/network/interfaces

if thats the case then your may just need to set a default route type
at the command line and post the output.

You're using FF3? There is a well known issue where FF3 checks with the networkmanager (NM) to see if the net is up. If you have dialup or anything using ppp, or some wireless setups then NM tells FF there's no 'net connection and FF browses in "offline mode" (aka totally useless mode).

From FF3:
File > Work Offline (uncheck)

Removing "network-manager" (using eg synaptic) worked for me.

See eg https://bugs.launchpad.net/usb-adsl-...er/+bug/191889 and note that the about:config setting doesn't work for me (though it did the first time I tried it, bizarrely).