Thanks a lot for all the suggestions. I made a fresh install and followed all the suggestions carefully and now the internet is working, tho the connection speed is very slow. So to open a page it takes a while. I can ping web pages but after a while the speed goes so slow that everythings stops. I don't know why this happens since when i use windows with the same type of connection i get a faster connection. Have seen that many people have had this problem in this forum, but couldn't see any real solution to it. Any suggestion will be welcomed

Possibly crap or wrong drivers for your modem?

This is what i found, rempompiling my 2.6.5 kernel, in the section networking support/networking options/network packet filtering/netfilter configuration:

TCPMSS target support (IP_NF_TARGET_TCPMSS)

This option adds a `TCPMSS' target, which allows you to alter the
MSS value of TCP SYN packets, to control the maximum size for that
connection (usually limiting it to your outgoing interface's MTU
minus 40).

This is used to overcome criminally braindead ISPs or servers which
block ICMP Fragmentation Needed packets. The symptoms of this
problem are that everything works fine from your Linux
firewall/router, but machines behind it can never exchange large
packets:
1) Web browsers connect, then hang with no data received.
2) Small mail works fine, but large emails hang.
3) ssh works fine, but scp hangs after initial handshaking.

Workaround: activate this option and add a rule to your firewall
configuration like:

iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \
-j TCPMSS --clamp-mss-to-pmtu

To compile it as a module, choose M here. If unsure, say N.

Hope that can help you.

Mmm, i've just solved a slow modem problem with setting a 56k to 33k in kppp. Now it works fine.