no connection to the internet .. but only on one PC in my network

This drives me mad.... one of my PC's (in W98 network) now refuses to
connect to the internet (through Alcatel ADSL wireless modem). Problem
appears in IE6 and in OE.

Within the network, all PC's see eachother though (windows explorer)

The modem has no setting activated to prevent this pc to go to the internet
to my knowledge.

Settings of all PC's seem to be equal - is there some test possible, or
mystery setting I forgot?

Thanks!

=Erwan=